Shock absorbing steering apparatus

ABSTRACT

A shock absorbing steering apparatus for use in a vehicle, including a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, and wherein one of the steering column and the portion of the vehicle body includes a mounting portion, while the other of the steering column and the portion of the vehicle body includes a holding portion. The steering apparatus further includes an impact energy absorbing member to be mounted on the mounting portion. The impact energy absorbing portion includes an engaging portion engageable with the holding portion and is deformable as the steering column is moved in the forward direction while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision.

TECHNICAL FIELD

The present invention relates to a shock absorbing steering apparatusfor use in a vehicle, which includes a steering column as a majorelement and which is provided with an impact energy absorbing memberarranged to absorb an impact energy generated by a secondary collisionof an occupant (operator or driver) of the vehicle, upon a collision ofthe vehicle.

BACKGROUND ART

The steering apparatus of this type is arranged such that in the eventof a secondary collision of the vehicle occupant or operator, forexample, with the steering wheel attached to the steering column, thesteering column is releasable from the body of the vehicle, and axiallymovable in the forward direction of the vehicle, while a force ofresistance to this movement of the steering column (namely, an impactenergy absorbing load) is generated. That is, an impact energy absorbingmember is provided to absorb an impact energy generated by the secondarycollision. Described more specifically, the impact energy absorbingmember is arranged, for example, to deform as the steering column ismoved in the forward direction of the vehicle, so that a force whichcauses the deformation of the impact energy absorbing member isgenerated as the impact energy absorbing load. JP-U-6-79690 andJP-Y2-6-45415 disclose examples of the steering apparatus of the typedescribed above.

The two examples of the steering apparatus disclosed in theabove-identified publications use an elongate metallic plate or stripcalled an energy absorbing plate (impact absorbing plate), as the impactenergy absorbing member. This energy absorbing plate is interposedbetween the steering column and a portion of the vehicle body. Describedin greater detail, the steering apparatus disclosed in JP-U-6-79690(herein after referred to as “first conventional apparatus) is providedwith a column holder structure (referred to as “column bracket” in thepublication) arranged to hold a column body, which is a major portion ofthe steering column. The energy absorbing plate has an intermediateportion in the form of a substantially U-shaped energy absorbing curvedportion, which is simply accommodated in a space formed between thecolumn body and the column holder structure. Further, the energyabsorbing plate has one end portion welded or otherwise fixed to anupper portion of the outer circumferential surface of the column body.In the steering apparatus disclosed in JP-Y2-6-45415 (herein afterreferred to as “second conventional apparatus), on the other hand, oneend portion of the energy absorbing plate is fastened to a portion ofthe vehicle body.

DISCLOSURE OF THE INVENTION

In the first conventional apparatus, the energy absorbing plate isrequired to be securely welded or otherwise fixed to the upper portionof the outer circumferential surface of the steering column, moreprecisely, of the column body. This requirement reduces ease ofassembling of the steering apparatus. In the second conventionalapparatus, the energy absorbing plate is required to be fastened to thevehicle body while the steering column is fixed to the vehicle body.This requirement increases complexity of the procedure to assemble thesteering apparatus with respect to the vehicle body. While the first andsecond conventional apparatuses described above suffer from thosedrawbacks, various other conventional steering apparatuses also sufferfrom specific drawbacks. In this respect, improvements to overcome thedrawbacks of the conventional steering apparatuses are needed to providean improved steering apparatus provided with an impact energy absorbingmember.

It is therefore an object of the present invention to provide a steeringapparatus which is improved in construction over the conventionalapparatuses. This object may be achieved according to the principle ofthis invention, which provides a shock absorbing steering apparatus foruse in a vehicle, comprising a steering column to be fixed to a portionof a body of the vehicle such that the steering column is releasablefrom the body of the vehicle and movable in a forward direction of thevehicle in the event of a secondary collision of an occupant of thevehicle, upon a collision of the vehicle, and wherein one of thesteering column and the above-indicated portion of the body of thevehicle includes a mounting portion, while the other of the steeringcolumn and the above-indicated portion includes a holding portion. Theshock absorbing steering apparatus further comprises an impact energyabsorbing member which is to be mounted on the mounting portion andwhich includes an engaging portion that is engageable with the holdingportion and deformable as the steering column is moved in the forwarddirection of the vehicle while the engaging portion is held inengagement with the holding portion, whereby the impact energy absorbingmember absorbs an impact energy generated by the secondary collision.

In the shock absorbing steering apparatus of the present inventionconstructed as described above, the impact energy absorbing member ismounted on only one of the steering column and the relevant portion ofthe vehicle body, so that the steering apparatus can be easily assembledwith respect to the vehicle body. Further, the impact energy absorbingmember is not required to be welded or otherwise fixed to one of thesteering column and the portion of the vehicle body, so that the impactenergy absorbing member can be simply and economically held in position.In addition, the impact energy absorbing member is not required to befastened to the other of the steering column and the portion of thevehicle body, so that steering column can be easily assembled withrespect to the vehicle body. Thus, the present shock absorbing steeringapparatus is improved in construction over the conventionalcounterparts.

It is noted that the shock absorbing steering apparatus described aboveis one fundamental form of the present invention, and that the presentinvention may be embodied in various other forms as discussed belowunder the heading “DETAILED DESCRIPTION OF THE INVENTION”, which haverespective specific features and advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view in axial cross section showing shockabsorbing steering apparatus constructed according to a first embodimentof this invention;

FIG. 2 is a plan view of the shock absorbing steering apparatus shown inFIG. 1;

FIG. 3 is an enlarged fragmentary side elevational view in axial crosssection showing a relationship among a body-side bracket, a break-awaybracket, a guide member, an energy absorbing plate and other elementsthat are shown in FIG. 1;

FIG. 4 is a plan view showing the relationship among the body-sidebracket, break-away bracket, guide member, energy absorbing plate andother elements shown in FIG. 3;

FIG. 5 is an enlarged fragmentary partially cut-away front elevationalview showing the relationship among the body-side bracket, break-awaybracket, guide member, energy absorbing plate and other elements shownin FIG. 1;

FIG. 6 is a rear elevational view showing the relationship among thebody-side bracket, break-away bracket, guide member, energy absorbingplate and other elements shown in FIGS. 3-5;

FIG. 7 is an enlarged side elevational view of the guide member shown inFIGS. 1-6;

FIG. 8 is a plan view of the guide member shown in FIG. 7;

FIG. 9 is a rear elevational view of the guide member shown in FIG. 7;

FIG. 10 is an enlarged fragmentary front elevational view showing arelationship between the guide member and energy absorbing plate shownin FIG. 3;

FIG. 11 is a fragmentary side elevational view in axial cross sectionshowing a modification of the shock absorbing steering apparatus of thefirst embodiment shown in FIGS. 1-10;

FIG. 12 is a fragmentary side elevational view in axial cross sectionshowing a shock absorbing steering apparatus constructed according to asecond embodiment of this invention;

FIG. 13 is an enlarged perspective view of a rectangular three-sidedclip shown in FIG. 12;

FIG. 14 is a fragmentary side elevational view in axial cross sectionshowing a modification of the shock absorbing steering apparatus of thesecond embodiment shown in FIG. 12;

FIG. 15 is a fragmentary perspective view of a shock absorbing steeringapparatus constructed according to a third embodiment of the invention;

FIG. 16 is a fragmentary side elevational view showing a firstmodification of the shock absorbing steering apparatus of the thirdembodiment shown in FIG. 15;

FIG. 17A is an enlarged perspective view of a guide member and a bindingband shown in FIG. 16, and FIG. 17B is a fragmentary perspective view ofa break-away bracket shown in FIG. 16;

FIG. 18 is a fragmentary perspective view showing a second modificationof the shock absorbing steering apparatus of the third embodiment,wherein the guide member and binding band shown in FIGS. 16 and 17 areformed integrally with each other;

FIG. 19 is a fragmentary side elevational view in axial cross sectionshowing a third modification of the shock absorbing steering apparatusof the third embodiment shown in FIG. 15;

FIG. 20 is a fragmentary side elevational view in axial cross sectionshowing a fourth modification of the shock absorbing steering apparatusof the third embodiment of FIG. 15;

FIG. 21 is a fragmentary perspective view schematically illustrating ashock absorbing steering apparatus constructed according to a fourthembodiment of this invention;

FIG. 22 is a fragmentary exploded perspective view showing a shockabsorbing steering apparatus constructed according to a fifth embodimentof the present invention;

FIG. 23 is an enlarged fragmentary side elevational view in axial crosssection showing a relationship among a break-away bracket, a guidemember, an energy absorbing plate and other elements that are shown inFIG. 22;

FIG. 24 is a plan view showing the relationship among the break-awaybracket, guide member, energy absorbing plate and other elements shownin FIG. 23;

FIG. 25 is a fragmentary front elevational view in axial cross sectionshowing a relationship among a communication hole of the break-awaybracket, guide member, energy absorbing plate and other elements shownin FIG. 24;

FIG. 26 is an enlarged fragmentary side elevational view in axial crosssection corresponding to that of FIG. 23, showing a first modificationof the shock absorbing steering apparatus of the fifth embodiment shownin FIGS. 22-24;

FIG. 27 is a fragmentary end view in axial cross section showing arelationship between a pair of engaging jaws and a pair of engagingprojections of the guide member shown in FIG. 26;

FIG. 28 is a fragmentary exploded plan view showing a secondmodification of the shock absorbing steering apparatus of the fifthembodiment, wherein the pair of engaging projections of the guide memberare formed integrally with a pair of upper holding pieces;

FIG. 29 is a rear elevational view of the guide member shown in FIG. 28;

FIG. 30 is a fragmentary plan view showing a third modification of theshock absorbing steering apparatus of the fifth embodiment shown inFIGS. 22-24;

FIG. 31 is a side elevational view in axial cross section showing ashock absorbing steering apparatus constructed according to a sixthembodiment of this invention;

FIG. 32 is a plan view of the shock absorbing steering apparatus shownin FIG. 31;

FIG. 33 is an enlarged fragmentary partially cut-away rear elevationalview showing a relationship among a body-side bracket, a break-awaybracket, an energy absorbing plate and other elements that are shown inFIG. 31;

FIG. 34 is a side elevational view in axial cross section taken alongline M-M of FIG. 33;

FIG. 35 is a perspective view of the energy absorbing plate shown inFIGS. 31-34;

FIG. 36 is a fragmentary perspective view showing an energy absorbingplate employed in a first modification of the shock absorbing steeringapparatus of the sixth embodiment shown in FIGS. 31-35;

FIG. 37 is a fragmentary perspective view showing a body-side bracketemployed in a second modification of the shock absorbing steeringapparatus of the sixth embodiment shown in FIGS. 31-35;

FIG. 38 is a fragmentary perspective view showing a body-side bracketand an energy absorbing plate that are employed in a third modificationof the shock absorbing steering apparatus of the sixth embodiment shownin FIGS. 31-35;

FIG. 39 is a fragmentary perspective view showing an energy absorbingplate employed in a fourth modification of the shock absorbing steeringapparatus of the sixth embodiment shown in FIGS. 31-35;

FIG. 40 is a fragmentary perspective view showing a body-side bracketand an energy absorbing plate employed in a fifth modification of theshock absorbing steering apparatus of the sixth embodiment shown inFIGS. 31-35;

FIG. 41 is a fragmentary plan view showing a shock absorbing steeringapparatus constructed according to a seventh embodiment of the presentinvention;

FIG. 42 is a fragmentary side elevational view in axial cross section ofsome elements of the shock absorbing steering apparatus shown in FIG.41;

FIG. 43 is a side elevational view in axial cross section for explainingan operation of the elements shown in FIG. 42;

FIG. 44 is a fragmentary plan view showing a first modification of theshock absorbing steering apparatus of the seventh embodiment shown inFIGS. 40-43;

FIG. 45 is a fragmentary plan view showing a second modification of theshock absorbing steering apparatus of the seventh embodiment shown inFIGS. 40-43;

FIG. 46 is a fragmentary side elevational view of some elements of theshock absorbing steering apparatus shown in FIG. 45;

FIG. 47 is a side elevational view for explaining an operation of theelements shown in FIG. 46;

FIG. 48 is a fragmentary perspective view showing a shock absorbingsteering apparatus constructed according to an eighth embodiment of thisinvention;

FIG. 49 is a fragmentary side elevational view in axial cross sectionshowing some elements of the shock absorbing steering apparatus shown inFIG. 48;

FIG. 50 is a side elevational view in axial cross section for explainingan operation of the elements shown in FIG. 49;

FIG. 51 is a fragmentary perspective view showing a modification of theshock absorbing steering apparatus of the eighth embodiment shown inFIGS. 48-50;

FIG. 52 is a fragmentary side elevational view in axial cross sectionshowing some elements of the shock absorbing steering apparatus shown inFIG. 51;

FIG. 53 is a side elevational view in axial cross section for explainingan operation of the elements shown in FIG. 52;

FIG. 54 is a side elevational view in axial cross section showing ashock absorbing steering apparatus constructed according to a ninthembodiment of the present invention;

FIG. 55 is a plan view of the shock absorbing steering apparatus shownin FIG. 54;

FIG. 56 is an enlarged fragmentary partially cut-away rear elevationalview showing a relationship among a body-side bracket, a break-awaybracket, an energy absorbing plate and other elements of the apparatusshown in FIG. 54;

FIG. 57 is a side elevational view in axial cross section taken alongline N-N of FIG. 56;

FIG. 58 is a perspective view of the energy absorbing plate shown inFIGS. 54-57;

FIG. 59 is a perspective view showing an energy absorbing plate employedin a modification of the shock absorbing steering apparatus of the ninthembodiment shown in FIGS. 54-57;

FIG. 60 is an enlarged fragmentary side elevational view showing a shockabsorbing steering apparatus constructed according to a tenth embodimentof the instant invention;

FIG. 61 is a fragmentary partially cut-away rear elevational viewshowing a relationship among a body-side bracket, a break-away bracket,an energy absorbing plate, a solenoid coil and other elements of theshock absorbing steering apparatus shown in FIG. 60;

FIG. 62 is a perspective view schematically illustrating therelationship among the body-side bracket and energy absorbing plate thatare shown in FIGS. 60 and 61;

FIG. 63 is an enlarged fragmentary partially cut-away rear elevationalview corresponding to that of FIG. 56, showing a shock absorbingsteering apparatus constructed according to an eleventh embodiment ofthis invention;

FIG. 64 is a perspective view schematically illustrating an energyabsorbing plate shown in FIG. 63;

FIG. 65 is a side elevational view in axial cross section correspondingto that of FIG. 57, showing a shock absorbing steering apparatusconstructed according to a twelfth embodiment of this invention;

FIG. 66 is a side elevational view showing a shock absorbing apparatusconstructed according to a thirteenth embodiment of the presentinvention;

FIG. 67 is a plan view of a steering column shown in FIG. 66;

FIG. 68 is a side elevational view in cross section of the steeringcolumn shown in FIG. 66;

FIGS. 69A and 69B are perspective views showing a rear tube of thesteering column shown in FIG. 66 as attached to the vehicle body, and ashock absorbing device provided in the thirteenth embodiment;

FIG. 70 is an enlarged view of a portion of a resistance generatingdevice, which is shown in FIG. 66;

FIG. 71 is an enlarged view of a portion of the resistance generatingdevice, which is shown in FIG. 68;

FIG. 72 is a perspective view showing grooves formed in a shockabsorbing plate of the resistance generating device shown in FIGS.66-71, and protrusions which are formed on a presser roller fordeformation of the shock absorbing plate and which are engageable withthe grooves;

FIG. 73 is a view indicating a relationship between a magnitude of aresisting force a generated by the resistance generating device shown,in FIGS. 66-71, and a moving speed v of a column moving portion;

FIGS. 74A and 74B are views showing a resistance generating deviceemployed in a shock absorbing steering apparatus constructed accordingto a fourteenth embodiment of the present invention;

FIGS. 75A and 75B are views showing a resistance generating deviceemployed in a shock absorbing steering apparatus which is a modificationof the fourteenth embodiment;

FIG. 76 is a side elevational view showing a shock absorbing steeringapparatus constructed according to a fifteenth embodiment of the instantinvention;

FIG. 77 is a plan view of a steering column shown in FIG. 76;

FIG. 78 is a side elevational view in cross section of the steeringcolumn shown in FIG. 76;

FIGS. 79A and 79B are perspective views showing a rear tube of thesteering column shown in FIG. 76, as attached to the vehicle body, and ashock absorbing device provided in the apparatus of FIG. 76;

FIG. 80 is a view corresponding to a side elevational view of thesteering column, showing the shock absorbing device shown in FIGS. 79Aand 79B;

FIG. 81 is a cross sectional view for explaining an arrangement of theshock absorbing device shown in FIGS. 79A and 79B;

FIGS. 82A and 82B are front elevational views of the shock absorbingdevice shown in FIGS. 79A and 79B;

FIGS. 83A and 83B are views showing the column moving portion in itsmoving state after it is released, in the shock absorbing device shownin FIGS. 79A and 79B;

FIG. 84 is a view corresponding to a side elevational view of thesteering column, showing the shock absorbing device provided in amodification of the shock absorbing steering apparatus of the fifteenthembodiment;

FIG. 85 is a perspective view showing a shock absorbing plate providedin a shock absorbing steering apparatus constructed according to asixteenth embodiment of this invention, and a portion of the apparatuson which the shock absorbing plate is mounted;

FIG. 86 is a cross sectional view of the portion of the apparatus onwhich the shock absorbing plate shown in FIG. 85 is mounted;

FIG. 87 is a cross sectional view of a portion of a modification of theshock absorbing steering apparatus of the sixteenth embodiment, on whicha shock absorbing plate is mounted; and

FIG. 88 is a cross sectional view showing a shock absorbing plateprovided in a shock absorbing steering apparatus constructed accordingto a seventeenth embodiment of this invention, and a portion of theapparatus on which the shock absorbing plate is mounted.

DETAILED DESCRIPTION OF THE INVENTION

There will be described in detail various forms of the steeringapparatus, which are considered inventive according to the principle ofthis invention. Each of these forms of the invention is numbered likethe appended claims and depends from the other form or forms, whereappropriate, for easier understanding of the technical featuresdisclosed in the present specification. It is to be understood that thepresent invention is not limited to the technical features or anycombinations thereof which will be described. It is to be furtherunderstood that a plurality of elements or features included in any oneof the following forms of the invention are not necessarily provided alltogether, and that the invention may be embodied with selected at leastone of the elements or features described with respect to the same form.It is to be still further understood that Japanese Patent ApplicationNos. 2003-136380, 2003-286678, 2004-049733, 2003-310419, 2003-279544 and2003-290149 on which the present application is based are incorporatedhereinto by reference.

(1) A shock absorbing steering apparatus for use in a vehicle,comprising:

-   -   a steering column to be fixed to a portion of a body of the        vehicle such that the steering column is releasable from the        body of the vehicle and movable in a forward direction of the        vehicle in the event of a secondary collision of an occupant of        the vehicle upon a collision of the vehicle, one of the steering        column and the above-indicated portion of the body of the        vehicle including a mounting portion, and the other of the        steering column and the above-indicated portion including a        holding portion; and    -   an impact energy absorbing member to be mounted on the mounting        portion, the impact energy absorbing member including an        engaging portion engageable with the holding portion and being        deformable as the steering column is moved in the forward        direction of the vehicle while the engaging portion is held in        engagement with the holding portion, whereby the impact energy        absorbing member absorbs an impact energy generated by the        secondary collision.

The shock absorbing steering apparatus described above is onefundamental form of the present invention. As described above, theimpact energy absorbing member provided in the present steeringapparatus is mounted on only one of the steering column and the relevantportion of the vehicle body, so that the steering apparatus can beeasily assembled with respect to the vehicle body. Further, the impactenergy absorbing member is not required to be welded or otherwise fixedto one of the steering column and the portion of the vehicle body, sothat the impact energy absorbing member can be simply and economicallyheld in position. In addition, the impact energy absorbing member is notrequired to be fastened to the other of the steering column and theportion of the vehicle body, so that steering column can be easilyassembled with respect to the vehicle body.

In the present application, the expression “the steering column isreleasable from the body of the vehicle and movable in a forwarddirection of the vehicle” is not necessarily interpreted to mean thatthe steering column as a whole is releasable and movable from thevehicle body, but may be interpreted to mean that only a rear portion ofa column body of the steering column is releasable and movable from thevehicle body, where the column body is contractible and extensible, forexample, where the column body is provided with a telescopic mechanism.Namely, the steering column has a portion which is releasable andmovable apart from the vehicle body. The expression “a forward directionof the vehicle” is not limited to a horizontal direction parallel to thelongitudinal direction of the vehicle. Where the steering column isinclined relative to the vertical or horizontal direction, for example,the impact energy is absorbed during a movement of the steering columnalong its inclined axis. In this case, the “forward direction of thevehicle” means a direction which is parallel to the longitudinaldirection of the vehicle and which is inclined with respect to thehorizontal direction. Namely, the expression “forward direction of thevehicle” should be interpreted to comprehend this direction, anddirections which more or less deviate from the horizontal directionparallel to the longitudinal direction of the vehicle. Similarinterpretation applies to the expressions “rearward direction of thevehicle”, “longitudinal direction of the vehicle”, etc.

Further, the expression “impact energy absorbing member to be mounted onthe mounting portion” is not interpreted to mean that the impact energyabsorbing member is to be welded or otherwise fixed to the mountingportion”, but is interpreted to mean that the impact energy absorbingmember is to be simply assembled with respect to the mounting portion.The impact energy absorbing member is preferably arranged to be easilyengageable with and disengageable from the mounting portion provided onone of the steering column and the relevant portion of the vehicle body;Since the impact energy absorbing member is deformable to absorb theimpact energy generated by the secondary collision indicated above, thisabsorbing member is desirably mounted on the above-indicated one of thesteering column and the portion of the vehicle body, such that theabsorbing member is displaceable relative to the above-indicated one ofthe steering column and the relevant portion of the vehicle body, inorder to absorb the impact energy. Further, the impact energy absorbingmember is preferably provided with a fitting or positioning portion forholding it in position with respect to the mounting portion.

(2) The shock absorbing steering apparatus according to theabove-described form (1), further comprising an engagement adjustingmechanism operable to permit or inhibit an engagement between theengaging portion of the impact energy absorbing member and the holdingportion.

In the above-described form (2) of the shock absorbing steeringapparatus, the impact energy absorbing member can be disabled tofunction even when the steering column is released from the vehicle bodyand moved in the forward direction relative to the vehicle body uponcollision of the vehicle. Where the impact energy absorbing memberincludes a U-shaped portion as described below, the engagement adjustingmechanism may be arranged to inhibit the engagement of the engagingportion of the impact energy absorbing member with the holding portion,for thereby preventing deformation of the U-shaped portion of the impactenergy absorbing member even when the steering column is moved in theforward direction relative to the vehicle body. Thus, the engagementadjusting mechanism makes it possible to permit or inhibit thefunctioning of the impact energy absorbing member to absorb thegenerated impact energy.

(3) The shock absorbing steering apparatus according to theabove-described form (2), wherein the engagement adjusting mechanismincludes an actuator operable between a first position for permittingthe engagement between the engaging portion and the holding portion, anda second for inhibiting the engagement.

In the above-described form (3) of the shock absorbing steeringapparatus wherein the impact energy absorbing member includes theactuator, the actuator may be arranged such that the holding portionprovided on the steering column or on the portion of the vehicle body ismoved by the actuator between an advanced position and a retractedposition for permitting and inhibiting the engagement between theengaging portion and the holding portion.

(4) The shock absorbing steering apparatus according to theabove-described form (3), wherein the engagement adjusting mechanism isarranged such that an impact energy absorbing load to be generated bydeformation of the impact energy absorbing member does not act on theactuator when the engaging portion is brought into engagement with theholding portion.

In the above-described form (4) of the shock absorbing steeringapparatus wherein the impact energy absorbing load does not act on theactuator of the engagement adjusting mechanism upon engagement of theengaging portion with the holding portion, the required size and cost ofmanufacture of the actuator can be reduced.

(5) The shock absorbing apparatus according to any one of theabove-described forms (2)-(4), wherein the engagement adjustingmechanism is operable to permit or inhibit the engagement between theengaging portion and the holding portion, on the basis of an output of asensor provided to detect a state of the vehicle or an occupant of thevehicle.

In the above-described form (5) of the steering apparatus, theengagement between the engaging portion and the holding portion ispermitted or inhibited depending upon the detected state of the vehicleor vehicle occupant, it is possible to change the impact energyabsorbing characteristic of the impact energy absorbing member. Wherethe sensor is provided to detect whether a seat belt is worn on thevehicle occupant, for example, the engagement adjusting mechanism may bearranged to permit the engagement between the engaging and holdingportions when the output of the sensor indicates that the seat belt isnot worn on the vehicle occupant. Where the sensor is provided to detecta running speed of the vehicle, for instance, the engagement adjustingmechanism may be arranged to permit the engagement when the detectedrunning speed of the vehicle is higher than a predetermined upper limit.

(6) The shock absorbing steering apparatus according to theabove-described form (2), wherein the engagement adjusting mechanismincludes a mechanism operable to cause the holding portion to bedisplaced by an amount corresponding to a magnitude of an impact appliedto the body of the vehicle upon the collision of the vehicle, and amechanism operable to permit the engagement between the engaging portionand the holding portion when the amount of displacement of the holdingportion is larger than a predetermined threshold.

In the above-described form (6) of the shock absorbing steeringapparatus, the impact energy absorbing member is enabled to function toabsorb the impact energy when the magnitude of the impact applied to thevehicle upon the vehicle collision has exceeded a predeterminedthreshold. The amount of the impact energy generated in the event of thesecondary collision principally changes with the magnitude of the impactapplied to the vehicle body upon the vehicle collision, so that theimpact energy generated in the event of the secondary collision can beeffectively and suitably absorbed by the impact energy absorbing member,depending upon the magnitude of the impact applied to the vehicle bodyupon the primary vehicle collision.

(7) The shock absorbing steering apparatus according to theabove-described form (6), wherein the mechanism operable to cause theholding portion to be displaced by the amount corresponding to themagnitude of the impact is arranged to cause a displacement of theholding portion by utilizing an inertia mass of the holding portion.

In the above-described form (7) of the steering apparatus, the holdingportion is displaced due to an inertial force acting thereon upon thevehicle collision, relative to the steering column or vehicle body onwhich the holding portion is provided, such that the amount ofdisplacement of the holding portion corresponds to the magnitude of theimpact applied to the vehicle body. In this arrangement of theengagement adjusting mechanism, the impact energy absorbing member ispermitted or inhibited to function to absorb the impact energy, bypurely mechanical means, without any electrical means, so that thesteering apparatus can be simplified in overall arrangement Thedisplacement of the holding portion may be a linear movement, a rotarymovement, or a combination of linear and rotary movements. Although theengagement adjusting mechanism in this form of the invention may permitthe holding portion to be displaced relative to the steering column orvehicle body, upon a normal operation of a braking system to brake thevehicle the engagement adjusting mechanism is preferably arranged toinhibit a substantial displacement of the holding portion upon thenormal braking operation, but permit a substantial displacement of theholding portion only in the event of the vehicle collision.

(8) The shock absorbing steering apparatus according to any one of theabove forms (1)-(7), wherein the impact energy absorbing member isarranged to be positioned relative to the mounting portion such that theengaging portion and the holding portion are spaced from each other by apredetermined free-running distance in the forward direction before thesteering column is moved in the forward direction relative to theportion of the body of the vehicle.

In the above-described form (8) of the steering apparatus, the provisionof the free-running distance or spacing between the engaging portion andthe holding portion makes it possible to delay a moment of absorption ofthe impact energy by the impact energy absorbing member, with respect toa moment at which the steering column is released and moved from thevehicle body. Accordingly, an impact generated in the initial period ofthe secondary collision can be made smaller in the present arrangement,than in an arrangement in which the engaging portion is brought intoengagement with the holding portion as soon as the movement of thesteering column relative to the vehicle body is initiated. It is notedthat the moment at which the impact energy is absorbed by the impactenergy absorbing member can be suitably adjusted as needed by adjustingthe free-running distance.

(9) The shock absorbing steering apparatus according to the above form(8), wherein one of the engaging portion and the holding portionincludes a recessed part which has a recess engageable with the other ofthe engaging and holding portions and which cooperates with the other ofthe engaging and holding portions to define therebetween thepredetermined free-running distance.

In the above-described form (9) of the steering apparatus, the recessedpart functions as guiding means for guiding a relative movement of theengaging and holding portions until the relative movement is stopped atthe end of the recess part. Thus, the recessed part assures highstability of holding of the engaging portion by the holding portion.Further, the above-indicated free-running distance is provided betweenor defined by the end of the recessed part and the above-indicated otherof the engaging and holding portions. In the presence of the recessedpart, the provision of the free-running distance does not require theengaging portion to be spaced a large distance apart from the end of theholding portion before the forward movement of the steering column.

(10) The shock absorbing steering apparatus according to any one of theabove-described forms (1)-(9), further comprising an initial-loadadjusting mechanism operable to reduce a rate of increase of an impactenergy absorbing load to be generated by deformation of the impactenergy absorbing member in an initial period of the absorption of theimpact energy, the initial-load adjusting mechanism being provided at atleast one position selected from among: a position between the impactenergy absorbing member and the steering column; a position on theimpact energy absorbing member; and a position between the impact energyabsorbing member and the steering column.

In the above-described form (10) of the steering apparatus including theinitial-load adjusting mechanism, the impact energy absorbing load isincreased at a relatively low rate in an initial period of absorption ofthe impact energy by the impact energy absorbing member, that is, in aninitial period of operation of the impact energy after the engagement ofthe engaging portion with the holding portion. Accordingly, the impactenergy can be smoothly absorbed, without an abrupt increase of theimpact energy absorbing load which would cause an accordingly largeimpact on the vehicle operator or occupant.

(11) The shock absorbing steering apparatus according to any one of theabove-described forms (1)-(10), wherein the engaging portion of theimpact energy absorbing member and the holding portion are engageablewith each other so as to provisionally hold the steering column on theportion of the body of the vehicle through the impact energy absorbingmember when the steering column is fixed to the portion of the body ofthe vehicle.

In the above-described form (11) of the steering apparatus, the steeringcolumn can be easily assembled with respect to the vehicle body.

(12) The shock absorbing steering apparatus according to any one of theabove-described forms (1)-(11), wherein the impact energy absorbingmember is a plate having an end portion formed as the engaging portion.

In the above-described form (12) of the steering apparatus, the impactenergy absorbing member takes the form of a plate. For example, theimpact energy absorbing member may be a generally elongate strip whichis deformed as the steering column is moved relative to the vehiclebody, such that an originally straight portion of the strip is curved orbent while an originally curved portion of the strip is straightened.The impact energy generated in the event of the secondary collision isabsorbed by an impact energy absorbing load-generated due to a force ofresistance to the deformation of the strip. Where the impact energyabsorbing member is constituted by a plate, the steering apparatus canemploy a simple impact energy absorbing mechanism. Further, the impactenergy absorbing load can be easily adjusted by suitably determining thethickness and width of the plate. The present form of the steeringapparatus is further advantageous in that the impact energy absorbingplate is simple in construction with one end portion thereof beingformed as the engaging portion engageable with the holding portion.Accordingly, the steering apparatus is simplified in construction, witha relatively small number of components, without using an exclusivelydesigned separate member as the engaging portion. The impact energyabsorbing member in the form of a plate will be referred to as “anenergy absorbing plate” or “an impact energy absorbing plate” whereappropriate.

(13) The shock absorbing steering apparatus according to the above form(12), wherein the engaging portion and the holding portion are arrangedsuch that the engaging portion receives a shearing load after theengaging portion is brought into engagement with the holding portion.

In the above-described form (13) of the steering apparatus wherein theengaging portion formed at one end portion of the energy absorbing platereceives a shearing load or stress after the engagement with the holdingportion, the engaging portion provides required degrees of strength andrigidity even where the engaging portion has relatively small thicknessand width dimensions. The thickness of a portion of the plate which isto be deformed, and the width dimensions of the engaging portion and theother portions of the plate can be determined as need for the energyabsorbing plate to be able to exhibit the desired energy absorbingcharacteristics while assuring the required strength and rigidity of theengaging portion.

The above-described form (13) is preferable particularly where theengaging portion of the energy absorbing plate and the holding portionare engageable with each other so as to provisionally hold the steeringcolumn on the portion of the body of the vehicle when the steeringcolumn is fixed to the portion of the body of the vehicle, as describedabove. In the first conventional apparatus described above under theheading of BACKGROUND ART, the energy absorbing plate has an engagingportion formed by bending one of its opposite end portions. This bentengaging portion (provisionally holding hook portion) receives a bendingload or stress acting thereon so as to bend it back, when the bentengaging portion is in engagement with the holding portion toprovisionally hold the steering column on the vehicle body when thesteering column is fixed to the vehicle body. Accordingly, the energyabsorbing plate is required to have relatively large thickness and widthdimensions so that the plate has strength and rigidity sufficient toresist the bending at the engaging portion (provisionally holding hookportion). In the present steering apparatus wherein the engaging portionis subjected to a shearing load or stress when the engaging portion andholding portions are held in engagement with each other so as toprovisionally hold the steering column on the vehicle body. Accordingly,the required thickness of the energy absorbing plate at its engagingportion is comparatively small, and the required overall weight of theenergy absorbing plate is accordingly reduced.

(14) The shock absorbing steering apparatus according to theabove-described form (12) or (13), wherein the impact energy absorbingmember includes a plurality of plates which are superposed on each otherand each of which has the engaging portion.

In the above-described form (14) of the steering apparatus, theabsorption of the impact energy by each of the plates of the energyabsorbing member can be selectively permitted or inhibited so that thetotal amount of absorption of the impact energy by the energy absorbingmember can be changed in a plurality of steps, by means of theengagement adjusting mechanism described above with respect to the forms(2)-(7). For instance, an actuator is provided to move the holdingportion to a selected one of a plurality of positions, for permitting orinhibiting the engagement of each of the engaging portions of the plateswith the holding portion, to thereby change the total amount ofabsorption of the impact energy by the energy absorbing member.

(15) The shock absorbing steering apparatus according to any one of theabove-described forms (12)-(14), wherein the impact energy absorbingplate includes a generally U-shaped portion consisting of a curvedsection and two arm sections extending from respective opposite ends ofthe curved section, the impact energy absorbing member being arranged tobe mounted on the mounting portion such that the two arm sections extendin a direction almost parallel to a direction of movement of thesteering column relative to the portion of the body of the vehicle andsuch that the mounting portion is sandwiched by and between the two armsections in a direction of thickness of the plate of the energyabsorbing member, the impact energy absorbing member being deformed byone end portion of the mounting portion, during the movement of thesteering column relative to the portion of the body of the vehicle inthe forward direction of the vehicle with the engaging portion held inengagement with the holding portion, such that a position of the curvedsection in the impact energy absorbing member is gradually changed,whereby the impact energy generated by the secondary collision isabsorbed in the process of deformation of the impact energy absorbingmember.

In the above-described form (15) of the steering apparatus, the impactenergy absorbing member can be mounted or fitted on the mountingposition such that the mounting portion is sandwiched by and between thetwo arm sections of the generally U-shaped portion of the impact energyabsorbing member. Before the steering column is moved forward relativeto the vehicle body with the engaging portion held in engagement withthe holding portion, the U-shaped portion functions as a portion forholding the impact energy absorbing member on the mounting portion. Inthe process of the forward movement of the steering column with theengaging portion held in engagement with the holding portion, thegenerally U-shaped portion of the impact energy absorbing member isdisplaced relative to the mounting portion and is plastically deformedin pressing sliding contact with the above-indicated one end portion ofthe mounting portion, such that an instantly straight portion of the armsection which is on one side of the curved section remote from theengaging portion is continuously curved along the mounting portion whilean end portion of the instantly curved section which is adjacent to theother arm section is continuously straightened into that arm section.Thus, the impact energy absorbing member functions to absorb the impactenergy with high stability, in the process of its plastic deformation.

(16) The shock absorbing steering apparatus according to theabove-described form (15), wherein the engaging portion is formedintegrally with one of the two arm sections such that the engagingportion extends, from one end of that one arm section which is remotefrom the curved section, in a direction away from the other of the twoarm sections.

In the above-described form (16) of the steering apparatus, the engagingportion of the impact energy absorbing member can be easily formed bybending the free end portion of one of the two arm sections of thegenerally U-shaped portion. The engaging portion may be configured asneeded depending upon the function to be achieved by the engagingportion.

(17) The shock absorbing steering apparatus according to any one of theabove-described forms (1)-(16), wherein the steering column includes acolumn body, and a column holder structure which holds the column bodyand which is fixed to the portion of the body of the vehicle such thatthe column holder structure is releasable and movable away from theportion of the body of the vehicle in the event of the secondarycollision, and the column holder structure includes the mounting portionwhile the portion of the body of the vehicle is provided with theholding portion.

In the above-described form (17) of the steering apparatus, the steeringcolumn includes the column holder structure including the mountingportion on which the impact energy absorbing member is to be mounted. Anoperation to assemble the impact energy absorbing member with respect tothe steering column which is then mounted on the vehicle body is easierthan an operation to assemble the impact energy absorbing member withrespect to the vehicle body on which the steering column is thenmounted. The arrangement according to the above-described form (17)permits higher efficiency of assembling of the steering apparatus.

(18) The shock absorbing steering apparatus according to theabove-described form (17), wherein the column holder structure includesa pair of arms which are spaced apart from each other in a lateraldirection of the vehicle, and a central portion which is located almostintermediate between the pair of arms in the lateral direction, thecolumn holder structure being fixed at the pair of arms to the portionof the body of the vehicle, and the mounting portion being located inthe central portion of the column holder structure.

In the above-described form (18) of the steering apparatus, the impactenergy absorbing member is mounted in the almost laterally central partof the column holder structure. Thus, the space in the almost laterallycentral part of the column holder structure is effectively utilized forinstallation of the impact energy absorbing member. This arrangement isdesirable particularly where the steering apparatus employs only oneelement as the impact energy absorbing member.

(19) The shock absorbing steering apparatus according to theabove-described form (17) or (18), wherein the column holder structureholds the column body through a tilting mechanism.

In the first conventional apparatus described above, the impact energyabsorbing member is fixed to the column body, so that the energyabsorbing characteristic of the impact energy absorbing member may varywhen the column body is supported by the vehicle body through a tiltingmechanism, which permits an angle of tilting of the column body in avertical plane parallel to the longitudinal direction of the vehicle. Inthe above-described form (19) of the steering apparatus, the columnholder structure on which the impact energy absorbing member is mountedis not vertically moved even when the column body is vertically tilted.Thus, the impact energy absorbing member functions as intendedirrespective of a tilting motion of the steering column by the tiltingmechanism. In other words, the present steering apparatus wherein theimpact energy absorbing member is not fixed to the column body can beeasily equipped with the tilting mechanism, without an adverse influenceof the tilting mechanism on the energy absorbing characteristic of theimpact energy absorbing member.

(20) The shock absorbing steering apparatus according to any one of theabove-described forms (17)-(19), wherein the column holder structureholds the column body through a telescopic mechanism.

In the first conventional apparatus wherein the impact energy absorbingmember is fixed to the column body, the energy absorbing characteristicof the impact energy absorbing member may vary when the column body issupported by the vehicle body through a telescopic mechanism, whichpermits a change in the axial length of the column body. This variationis similar to that when the column body is supported by the vehicle bodythrough a tilting mechanism described above. In the above-described form(20) of the steering apparatus, the impact energy absorbing memberfunctions as intended irrespective of an operation of the telescopicmechanism to adjust the axial position of an axial portion of the columnbody at which the column body is supported by the column holderstructure. Thus, the present steering apparatus wherein the impactenergy absorbing member is not fixed to the column body can be easilyequipped with the telescopic mechanism, without an adverse influence ofthe telescopic mechanism on the energy absorbing characteristic of theimpact energy absorbing member.

(21) The shock absorbing steering apparatus according to any one of theabove-described forms (17)-(20), wherein the impact energy absorbingmember is a plate, and includes a generally U-shaped portion consistingof a curved section and two arm sections extending from respectiveopposite ends of the curved section, and one of the two arm sectionsincludes an end portion terminating in the engaging portion, the impactenergy absorbing member being arranged to be mounted on the mountingportion such that the two arm sections extend in a direction almostparallel to a direction of movement of the steering column relative tothe portion of the body of the vehicle and such that the mountingportion is sandwiched by and between the two arm sections in a directionof thickness of the plate of the impact energy absorbing member, theimpact energy absorbing member being deformed by a front end portion ofthe mounting portion, during the movement of the steering columnrelative to the portion of the body of the vehicle in the forwarddirection of the vehicle with the engaging portion held in engagementwith the holding portion, such that a position of the curved section inthe impact energy absorbing member is gradually changed, whereby theimpact energy generated by the secondary collision is absorbed in theprocess of deformation of the impact energy absorbing member.

In the above-described form (21) of the steering apparatus, the impactenergy absorbing member takes the form of a plate which includes agenerally U-shaped portion and which is mounted on the column holderstructure of the column body of the steering column. This plateincluding the generally U-shaped portion has been described above withrespect to the form (15) of this invention. Preferably, the arm sectionof the plate which includes the engaging portion is located nearer tothe holding portion. Where the steering column is fixed to a lowerportion of a reinforcement of an instrument panel of the vehicle body(which corresponds to the above-indicated portion of the body of thevehicle) such that the mounting portion is sandwiched by and between thetwo arm sections in the vertical direction, for example, the engagingportion is preferably formed so as to extend from the free end of theupper one of the two arm sections.

The above-described first conventional apparatus also employs an impactenergy absorbing plate including a generally U-shaped intermediate bentportion for absorbing the impact energy. However, the impact energyabsorbing plate is fixed at its one end to the column body, and thecolumn body is then assembled with respect to a portion of the vehiclebody through a column holder structure (which is referred to as thecolumn bracket, in the publication JP-U-6-79690). In this arrangement,it is difficult to assemble the impact energy absorbing plate withrespect to the vehicle body, with high accuracy of positioning of theplate relative to the vehicle body. In the above-described form (21) ofthe steering apparatus, however, the impact energy absorbing plate isheld by only the column holder structure, so that the accuracy ofpositioning of the plate relative to the vehicle body can besignificantly improved.

In the first conventional apparatus, the generally U-shaped bent portionis merely accommodated in a space formed between the column body and thecolumn holder structure, so that the impact energy absorbing plate maynot be deformed as intended at its bent portion, leading to a risk ofinstability of absorption of the impact energy by the deformation of theimpact energy absorbing plate. Namely, the impact energy absorbing platetends to suffer from a variation in its impact energy absorbingcharacteristic. In the above-described form (21) of this invention, onthe other hand, the generally U-shaped portion of the impact energyabsorbing plate is plastically deformed by the front end portion of thecolumn holder structure, more specifically, by the front end portion ofthe mounting portion of the column holder structure. Accordingly, thegenerally U-shaped portion of the plate can be deformed as intended,along the front end of the mounting portion of the column holderstructure, assuring high stability of absorption of the impact energy bythe plastic deformation of the generally U-shaped portion of the plate.

(22) The shock absorbing steering apparatus according to theabove-described form (21), wherein the engaging portion is formedintegrally with one of the two arm sections such that the engagingportion extends, from one end of the end portion of the above-indicatedone arm section which end is remote from the curved section, in adirection away from the other of the two arm sections.

In the above-described form (22) of the steering apparatus employing theimpact energy absorbing plate which includes the generally U-shapedportion and which is mounted on the column holder structure, theengaging portion of the plate is formed as described above with respectto the form (16) of this invention.

(23) The shock absorbing steering apparatus according to theabove-described form (21) or (22), wherein the front end portion of themounting portion is formed as a guide portion for guiding a displacementof the curved section of the impact energy absorbing member along of thefront end portion while the impact energy absorbing member is deformed.

The guide portion of the mounting portion provided in theabove-described form (23) of the steering apparatus functions to guidethe displacement of the impact energy absorbing plate relative to thecolumn holder structure, so as to cause deformation of the plate alongthe front end portion of the mounting portion. Preferably, the curvedsection has an arcuate or part-cylindrical shape, and the guide portionhas a semi-cylindrical shape so that the plate is deformed along asemi-cylindrical outer surface of the semi-cylindrical guide portion. Toassure smooth deformation of the impact energy absorbing plate, thesurface of the guide portion for sliding contact with the platepreferably has a relatively low coefficient of friction, to prevent alarge force of friction between the contacting surfaces of the plate andthe guide portion.

(24) The shock absorbing steering apparatus according to theabove-described form (23), wherein the mounting portion of the columnholder structure consists of two plates which are superposed on eachother such that one end portion of one of the two plates projects from acorresponding front end face of the other of the two plates in theforward direction of the vehicle, and the guide portion of the mountingportion is constituted by a guide member which is generally J-shaped incross section and which has a short arm and a long arm, the guide memberbeing fitted on the above-indicated one end portion of said one platesuch that a rear end face of the short arm is held opposed to the frontend face of the above-indicated other plate.

The steering apparatus according to the above-described form (24) isarranged to absorb the impact energy with high stability, with a simpleand inexpensive structure. In the second conventional apparatusdescribed above, the column holder structure is provided in its frontend portion with a U-shaped mounting portion on which a guide member ismounted. This U-shaped mounting portion requires a relatively high costto form, and tends to be easily bent due to a load applied theretothrough the guide member when the U-shaped impact energy absorbing plateis deformed to absorb the impact energy. Thus, this conventionalarrangement tends to suffer from instability of absorption of the impactenergy.

Contrary to the second conventional apparatus, the steering apparatusaccording to the above-described form (23) is arranged such that thegenerally J-shaped guide member which receives a load when the U-shapedimpact energy absorbing plate is deformed by the guide member to absorbthe impact energy is fitted on one end portion of one of the two plateswhich constitute a base portion of the column holder structure and whichare superposed on each other such that the above-indicated one endportion of one of the two plates projects from the corresponding end ofthe other plate in the forward direction of the vehicle. To mount theguide member on the mounting portion, it is not necessary to bend anyportion of the mounting portion, since the guide member is merely fittedon the above-indicated projecting front one end portion of one of thetwo plates of the mounting portion. Accordingly, the cost required toform the mounting portion can be reduced. Further, the projecting frontend portion of the above-indicated one plate has a comparatively highstrength, and is highly resistant to a bending load received through theguide member, so that the U-shaped impact energy absorbing plate isdeformed as intended to absorb the impact energy, assuring a high degreeof stability of absorption of the impact energy by deformation of theU-shaped impact energy absorbing plate. In addition, the presentsteering apparatus is advantageous in that the U-shaped impact energyabsorbing plate is displaced while the arm section of the U-shapedportion of the impact energy absorbing plate which corresponds to theshort arm of the guide member can be held in contact with or closeproximity to the surface of the other plate of the mounting portion,since the short arm is held opposed to the front end face of that otherplate. Accordingly, the required dimension of the mounting portion inthe direction in which the two plates are superposed on each other canbe reduced.

(25) The shock absorbing steering apparatus according to theabove-described form (23), wherein the mounting portion of the columnholder structure includes a plate having a generally U-shaped projectingend portion which constitutes the guide portion.

In the above-described form (25) of the steering apparatus, the mountingportion does not include the guide member described above with respectto the form (24), and the generally U-shaped projecting end portion ofthe base plate of the column holder structure functions as the guideportion. The present mounting portion not using a separate guide memberis simple in construction.

(26) The shock absorbing steering apparatus according to any one of theabove-described forms (23)-(25), wherein the impact energy absorbingmember is mounted on the mounting portion such that there is an air gapbetween the curved section and the guide portion.

In the above-described form (26) of the steering apparatus, the frontend portion of the mounting portion of the column holder structure ispermitted to be moved forward through the air gap during an initialportion of the forward movement of the steering column relative to thevehicle body, so that the moment of absorption of the impact energy bydeformation of the generally U-shaped portion of the impact energyabsorbing plate by the front end portion of the mounting portion isdelayed with respect to the moment at which the column holder structureis released from the vehicle body. Accordingly, an impact generated inthe initial period of the secondary collision can be made smaller in thepresent arrangement, than in an arrangement in which there is not an airgap between the curved section of the impact energy absorbing plate andthe guide portion. Further, the moment at which the impact energy isabsorbed by the deformation of the impact energy absorbing plate can besuitably adjusted as needed by adjusting the amount of the air gap.

(27) The shock absorbing steering apparatus according to any one of theabove-described forms (21)-(26), further comprising positioning andholding means for positioning and holding the above-indicated one armsection of the impact energy absorbing member with respect to the columnholder structure.

In the above-described form (27) of the steering apparatus, firstembodiment, the above-indicated one arm section of the generallyU-shaped portion of the impact energy absorbing plate is positioned andheld with respect to the column holder structure, by the positioning andholding means. The positioning and holding means assures stableengagement of the engaging portion of the impact energy absorbing platewith the holding portion provided on the vehicle body, with theabove-indicated one arm section being positioned relative to the columnholder structure, when the column holder structure is moved, togetherwith the steering column, relative to the vehicle body. The stableengagement of the engaging portion with the holding portion is permittedeven in the presence of the free-running distance between the holdingportion provided on the vehicle body and the engaging portion formedintegrally with the relevant arm section of the impact energy absorbingplate. Where the engaging portion of the, impact energy absorbing plateand the holding portion are engageable with each other so as toprovisionally hold the steering column on the vehicle body when thesteering column is fixed to the vehicle body, the positioning andholding means is effective to minimize dislocation of theabove-indicated one arm section of the impact energy absorbing platerelative, to the column holder structure, thereby facilitating theassembling of the steering column with respect to the vehicle body, forinstance, an operation to fix the column holder structure to the vehiclebody by using screws and nuts. The positioning and holding means isrequired to position the above-indicated arm section in at least one ofdirections of its width, thickness and length, and is preferablyarranged to position that arm section at least in the direction of width(in the lateral or transverse direction of the vehicle).

(28) The shock absorbing steering apparatus according to theabove-described form (27), wherein the positioning and holding meansincludes a pair of positioning and holding pieces disposed on oppositesides of the above-indicated one arm section such that the pair ofpositioning and holding pieces are spaced from each other in a directionof width of the above-indicated one arm section.

In the above-described form (28) of the steering apparatus, theabove-indicated one arm section of the impact energy absorbing plate canbe easily positioned by the pair of positioning and holding pieces,which may be simple in construction. These positioning and holdingpieces may be formed on a rear extension of the guide member which willbe described, or on any other part of the mounting portion.

(29) The shock absorbing steering apparatus according to heabove-described form (28), wherein the pair of positioning and holdingpieces have respective mutually opposed slant surfaces which are formedsuch that a distance between the opposed slant surfaces decreases in adirection from the above-indicated other arm section toward theabove-indicated one arm section.

In the above-described form (29) of the steering apparatus, the impactenergy absorbing plate can be positioned and held by the pair ofpositioning and holding pieces having the slant surfaces, irrespectiveof the specific width and thickness of the impact energy absorbingplate, even where the impact energy absorbing characteristic of theimpact energy absorbing plate is adjusted by suitably selecting thewidth and thickness dimensions of the impact energy absorbing plate.

(30) The shock absorbing steering apparatus according to theabove-described form (29), wherein the above-indicated one arm sectionof the generally U-shaped portion of the impact energy absorbing memberis supported by a portion of the mounting portion, at an inner surfaceof the above-indicated one arm section which faces inwardly of thegenerally U-shaped portion.

In the above-described form (30) of the steering apparatus, theabove-indicated one arm section is positioned by the pair of positioningand holding pieces and the above-indicated portion of the mountingportion, in a direction of thickness of the above-indicated on armsection. The above-indicated portion of the mounting portion whichsupports the above-indicated on one arm section may be provided on arear extension of the guide member which will be described, or on anyother part of the column holder structure, for example, on any portionof the column holder structure.

(31) The shock absorbing steering apparatus according to any one of theabove-described forms (28)-(30), wherein the engaging portion is formedintegrally with the above-indicated one arm section such that theengaging portion extends, from one end of the above-indicated one armsection which is remote from the curved section, in a direction awayfrom the other of the two arm sections and such that the engagingportion has a larger height than the pair of positioning and holdingpieces, as measured from an outer surface of the above-indicated one armsection that is opposite to an inner surface thereof which facesinwardly of the generally U-shaped portion, the engaging portion beingengageable at a free end portion thereof with the holding portion, andhaving a width smaller than a distance between the pair of positioningand holding pieces, at a height position of the engaging portion whichcorresponds to the height of the pair of positioning and holding pieces.

In the above-described form (31) of the steering apparatus, the U-shapedimpact energy absorbing plate can be mounted on the mounting portion ofthe column holder structure, by moving the impact energy absorbing platerelative to the mounting portion in a rearward direction of the vehiclesuch that the proximal or fixed end part of the engaging portion ispassed between the pair of positioning and holding pieces.

(32) The shock absorbing steering apparatus according to any one of theabove-described forms (27)-(31), wherein the mounting portion includes aguide member located at a front end portion thereof and operable toguide a displacement of the curved section of the impact energyabsorbing member while the impact energy absorbing member is deformed,and the guide member includes a rear extension extending in a rearwarddirection of the vehicle, the pair of positioning and holding meansbeing provided on the rear extension.

In the above-described form (32) of the steering apparatus, the guidemember provided at the front end portion of the mounting portion may begenerally J-shaped in cross section, as described above with respect tothe form (24) of this invention. In the present steering apparatus, theabove-indicated one arm section of the U-shaped impact energy absorbingplate is positioned and held with respect to the column holderstructure, by the positioning and holding means formed on the rearextension of the guide member, which rear extension is distant from thefront end portion of the guide member by which the impact energyabsorbing plate is deformed. This arrangement is effective to improvethe accuracy of positioning and holding of the above-indicated one armsection. This guide member may constitute the guide portion describedabove with respect to the form (23) of the present invention.

(33) The shock absorbing steering apparatus according to theabove-described form (32), wherein the rear extension of the guidemember includes a positioning and holding portion for positioning andholding the other of the two arm sections of the impact energy absorbingmember.

In the above-described form (33) of the steering apparatus, the U-shapedimpact energy absorbing plate is positioned and held at its two armsections by the guide member which is simple in construction and whichincludes the positioning and holding means and the positioning andholding portion. The guide member is effective to assure a high degreeof accuracy of positioning of the impact energy absorbing plate relativeto the column holder structure, more specifically, relative to themounting portion of the column holder structure.

(34) The shock absorbing steering apparatus according to theabove-described form (27), wherein the mounting portion includes asupporting portion, and the positioning and holding means includes agenerally rectangular three-sided clip having an elastically deformableportion which cooperates with the supporting portion to elastically holdtherebetween the above-indicated one arm section of the generallyU-shaped portion of the impact energy absorbing member in elasticallypressing contact therewith in a direction of thickness of theabove-indicated one arm section.

In the above-described form (34) of the steering apparatus, theabove-indicated one arm section of the U-shaped impact energy absorbingplate is elastically held in pressing contact with the elasticallydeformable portion of the rectangular three-side clip and the supportingportion of the mounting portion, in the direction of thickness of thatarm section, so as to assure high accuracy of positioning of the impactenergy absorbing plate with respect to the mounting portion. Since theclip includes the elastically deformable portion, the same clip can beused to hold the impact energy absorbing plate, irrespective of thespecific thickness of the plate, even where the impact energy absorbingcharacteristic of the impact energy absorbing plate is adjusted bysuitably selecting the thickness dimension of the impact energyabsorbing plate within a range of the amount of elastic deformation ofthe elastically deformable portion of the clip.

(35) The shock absorbing steering apparatus according to theabove-described form (27), wherein the mounting portion includes asupporting portion, and the positioning and holding means includes aholding band which cooperates with the supporting portion to hold theabove-indicated one arm section of the generally U-shaped portion of theimpact energy absorbing member, the holding band having a variableeffective length of holding.

In the above-described form (35) of the steering apparatus, theabove-indicated one arm section of the U-shaped impact energy absorbingplate is held by the holding band and the supporting portion of themounting portion. Since the effective holding length of the holding bandis variable, the same holding band can be used to hold the impact energyabsorbing plate, irrespective of the specific thickness and width of theplate, even where the impact energy absorbing characteristic of theimpact energy absorbing plate is adjusted by suitably selecting thethickness and width dimensions of the impact energy absorbing plate.Accordingly, the cost of manufacture of the steering apparatus isreduced.

(36) The shock absorbing steering apparatus according to any one of theabove-described forms (21)-(35), wherein the column holder structure hasa pair of slots which are spaced apart from each other in a lateraldirection of the vehicle and through which the column holder structureis attached to the portion of the body of the vehicle such that thecolumn holder structure is releasable and movable away from the portionof the body of the vehicle in the forward direction of the vehicle, thecolumn holder structure further including a central portion which islocated almost intermediate between the pair of slots in the lateraldirection and which includes the mounting portion on which the impactenergy absorbing member is mounted,

-   -   and wherein the impact energy absorbing member includes a pair        of wing portions which extend from the above-indicated one arm        section in respective opposite directions parallel to the        lateral direction of the vehicle and which are provided with        respective cylindrical portions which are respectively        press-fitted in the pair of slots of the column holder structure        and which are releasable from the pair of slots when the column        holder structure is moved away from the portion of the body of        the vehicle in the forward direction of the vehicle.

Where the above-described form (36) of the steering apparatus isarranged such that the engaging portion of the impact energy absorbingplate is used to provisionally hold the steering column on the vehiclebody when the steering column is fixed to the vehicle body, as describedabove with respect to the above-described form (11), the steering columnis supported by the vehicle body through the engaging portion and thewing portions of the impact energy absorbing member, so that the weightof the steering column does not act on the U-shaped portion of theimpact energy absorbing member, which U-shaped portion is to be deformedto absorb the impact energy. Thus, the present arrangement is effectiveto prevent undesirable deformation of the U-shaped portion of the impactenergy absorbing member upon assembling of the steering column withrespect to the vehicle body, and assures high stability of absorption ofthe impact energy by deformation of the U-shaped portion after thesteering column is mounted on the vehicle body. It is furtherappreciated that the pair of wing portions of the impact energyabsorbing member can function as the positioning and holding means forpositioning and holding the above-indicated one arm section of theimpact energy absorbing member, as described above with respect to theabove-described form (27). The pair of wings are desirably locatedrelatively near the engaging portion, preferably, adjacent to theengaging portion in the forward direction of the vehicle.

(37) The shock absorbing steering apparatus according to any one of theabove-described forms (21)-(35), further comprising anenergy-absorbing-load changing mechanism operable to change an impactenergy absorbing load to be generated by deformation of the impactenergy absorbing member, depending upon a velocity of the movement ofthe steering column in the forward direction of the vehicle relative tothe portion of the body of the vehicle.

The magnitude of the impact applied to the steering column upon thesecondary collision of the vehicle occupant (operator), for example,with the steering wheel, is not only determined depending upon whether aseat belt is worn on the vehicle occupant or not, but also determined bya kinetic energy of the vehicle occupant upon the secondary collision.Namely, the impact applied to the vehicle occupant and to the steeringcolumn increases with an increase in the kinetic energy of the vehicleoccupant, that is, varies depending also on various factors includingthe impact acting on the steering column and the weight of the vehicleoccupant colliding with the steering wheel. In this respect, it isdesirable to change the impact energy absorbing load to be generated bydeformation of the impact energy absorbing member, on the basis of aparameter indicative of the impact actually acting on the steeringcolumn, for effectively absorbing the impact energy. The steering columnis moved relative to the vehicle body by the kinetic energy of thevehicle occupant colliding with the steering wheel, so that the velocityof movement of the steering column increases with an increase in thekinetic energy of the vehicle occupant. Accordingly, the velocity ofmovement of the steering column can be suitably used as a parameterindicative of the impact actually acting on the steering column. In theabove-described mode (37), the energy-absorbing-load changing mechanismis provided to change the impact energy absorbing load, depending uponthe velocity of movement of the steering column, that is, depending uponthe magnitude of the impact actually applied to the steering column inthe event of the secondary collision of the vehicle occupant with thesteering wheel, so that the impact applied to the vehicle occupant iseffectively reduced by deformation of the impact energy absorbingmember, for thereby protecting the vehicle occupant from the impactgenerated by the secondary collision.

The term “velocity of movement of the steering column” used inconnection with the above-described form (36) is interpreted to mean avelocity at which the steering column is moved relative to a portion ofthe vehicle body at which the steering column is attached to the vehiclebody. The velocity used by the energy-absorbing-load changing mechanismmay be the velocity of movement of the steering column over its entiredistance of movement, or the velocity at any point of time during theentire distance or stroke of movement. Preferably, the velocity in arelatively initial period of the movement of the steering column is usedby the energy-absorbing-load changing mechanism, since this velocity ata relatively early point of time after the initiation of the movement ofthe steering column tends to accurately reflect the impact actuallyapplied to the steering column upon the secondary collision of thevehicle occupant with the steering wheel. The term “impact energyabsorbing load” is interpreted to mean a force of resistance to theforward movement of the steering column relative to the vehicle body.

The energy-absorbing-load changing mechanism provided in theabove-described form (36) may be constructed as needed to change theimpact energy absorbing load to be generated by deformation of theimpact energy absorbing member. For instance, the energy-absorbing-loadchanging mechanism includes an electric means such as an electricallyoperated actuator which is operated to control the impact energyabsorbing load, under the control of an electronic control device,according to a signal indicative of the detected velocity of movement ofthe steering column. Alternatively, the energy-absorbing-load changingmechanism includes a purely mechanical means operable according to theprinciple of dynamics. The use of mechanical means as described below ismore desirable for structural and control simplification and reductionof the cost of manufacture of the steering apparatus.

(38) The shock absorbing steering apparatus according to theabove-described form (37), wherein the energy-absorbing-load changingmechanism increases the impact energy absorbing load with an increase inthe velocity of movement of the steering column.

As discussed above, the velocity of movement of the steering columnincreases with an increase in the magnitude of the impact acting on thesteering column. On the other hand, the distance of movement of thesteering column for absorbing the impact energy is determined by thespecific construction of the steering apparatus, in particular, thespecific structure for mounting the steering column on the vehicle body.For effectively absorbing the impact energy within the predetermineddistance of movement of the steering column, it is desirable that theamount of the impact energy to be absorbed per unit distance of movementof the steering column increases with an increase in the velocity ofmovement of the steering column. This desire is satisfied in theabove-described form (38) of this invention, which is constructed so asto prevent bottoming of the steering column at the end of itspredetermined movement distance or stroke, which would cause aconsiderably large impact applied to the vehicle operator, when thesecondary collision of the vehicle operator with the steering wheelgenerates a relatively large impact energy, and so as to smoothly absorbthe impact energy over a relatively long distance of movement of thesteering column, when the secondary collision generates a relativelysmall impact energy.

(39) The shock absorbing steering apparatus according to theabove-described form (37) or (38), wherein the energy-absorbing-loadchanging mechanism changes the impact energy absorbing load such thatthe impact energy absorbing load is larger when the velocity of movementof the steering column is higher than a predetermined threshold, thanwhen the velocity is not higher than the predetermined threshold.

The impact energy absorbing load can be changed continuously accordingto the velocity of movement of the steering column, or alternativelychanged in steps depending upon the velocity of movement as in theabove-described form (39) of this invention. Namely, the impact energyabsorbing load is made relatively large when the velocity of movement ofthe steering column is higher than the predetermined threshold, andrelatively small when the velocity is, not higher than the threshold.The present steering apparatus capable of changing the impact energyabsorbing load in only two steps is comparatively simple in constructionof the energy-absorbing-load changing mechanism.

(40) The shock absorbing steering apparatus according to any one of theabove-described forms (37)-(39), wherein the energy-absorbing-loadchanging mechanism changes the impact energy absorbing load by changinga force of resistance to the deformation of the impact energy absorbingmember (372).

The impact energy absorbing load generated by deformation of the impactenergy absorbing member is relatively small when the impact energyabsorbing member in the form of a plate, for example, is relativelyeasily deformable, and is relatively small when the plate is relativelyhardly deformable. In the above-described form (40) of this invention,the force of resistance to the deformation of the impact energyabsorbing member is used as a parameter indicative of the force requiredto cause the deformation of the impact energy absorbing member, and ischanged to change the impact energy absorbing load. The term “force ofresistance to the deformation” is broadly interpreted to indicate adegree of difficulty to cause the deformation of the impact energyabsorbing member, and to comprehend not only a stress required to causethe deformation, but also a force of friction existing between theimpact energy absorbing member and the mounting member, which force offriction is a force of resistance to a displacement of the impact energyabsorbing member relative to the mounting portion.

(41) The shock absorbing steering apparatus according to theabove-described form (40), wherein the impact energy absorbing member isa plate, and includes a generally U-shaped portion consisting of acurved section and two arm sections extending from respective oppositeends of the curved section, and one of the two arm sections includes anend portion terminating in the engaging portion, the impact energyabsorbing member being arranged to be mounted on the mounting portionsuch that the two arm sections extend in a direction almost parallel toa direction of movement of the steering column relative to the portionof the body of the vehicle and such that the mounting portion issandwiched by and between the two arm sections in a direction ofthickness of the plate of the impact energy absorbing member, the impactenergy absorbing member being deformed by an end portion of the mountingportion, during the movement of the steering column relative to theportion of the body of the vehicle in the forward direction of thevehicle with the engaging portion held in engagement with the holdingportion, such that a position of the curved section in the impact energyabsorbing member is gradually changed, whereby the impact energygenerated by the secondary collision is absorbed in the process ofdeformation of the impact energy absorbing member,

-   -   and wherein the energy-absorbing-load changing mechanism        includes (a) a deformation-resistance increasing member provided        on the mounting portion and engageable with the impact energy        absorbing member so as to increase the force of resistance to        the deformation of the impact energy absorbing member, and (b)        an engaging mechanism operable to cause engagement of the        deformation-resistance increasing member with the impact energy        absorbing member when a velocity of movement of the impact        energy absorbing member relative to the front end portion of the        mounting portion is higher than a predetermined threshold.

In the above-described form (41) of the steering apparatus wherein theimpact energy absorbing member takes the form of a plate, theenergy-absorbing-load changing mechanism utilizes the impact energyabsorbing plate as a deformable member and the end portion of themounting portion as a forcing member for forcing the impact energyabsorbing plate so as to cause deformation of this plate, so that theimpact energy absorbing load is changed by changing a state ofengagement between the deformable member and the forcing member.Described more specifically, the energy-absorbing-load changingmechanism includes the deformation-resistance increasing member, whichfor example, takes the form of at least one projection projecting fromthe mounting portion, or alternatively a friction generating memberarranged to generate a large force of friction with respect to theimpact energy absorbing plate, so that the impact energy absorbing loadis increased by engagement of the at least one projection or thefriction generating member with the impact energy absorbing plate. Theseexamples of the energy-absorbing-load changing mechanism is consideredto employ a purely mechanical means operable according to the principleof dynamics, which is highly reliable in operation and simpler inconstruction and available at a lower cost than an electrical means.

(42) The shock absorbing steering apparatus according to theabove-described form (40), The shock absorbing steering apparatusaccording to claim 40, wherein the impact energy absorbing member is aplate, and includes a generally U-shaped portion consisting of a curvedsection and two arm sections extending from respective opposite ends ofthe curved section, and one of the two arm sections includes an endportion terminating in the engaging portion, the impact energy absorbingmember being arranged to be mounted on the mounting portion such thatthe two arm sections extend in a direction almost parallel to adirection of movement of the steering column relative to the portion ofthe body of the vehicle and such that the mounting portion is sandwichedby and between the two arm sections in a direction of thickness of theplate of the impact energy absorbing member, the impact energy absorbingmember being deformed by an end portion of the mounting portion, duringthe movement of the steering column relative to the portion of the bodyof the vehicle in the forward direction of the vehicle with the engagingportion held in engagement with the holding portion, such that aposition of the curved section in the impact energy absorbing member isgradually changed, whereby the impact energy generated by the secondarycollision is absorbed in the process of deformation of the impact energyabsorbing member,

-   -   and wherein the energy-absorbing-load changing mechanism        includes (a) a movable member provided on the mounting portion        and engageable with the impact energy absorbing member such that        the movable member is movable when the impact energy absorbing        member is displaced relative to the end portion of the mounting        portion, and (b) a movable-member-movement restricting mechanism        operable to restrict a movement of the movable member when a        velocity of movement of the movable member is higher than a        predetermined threshold.

In the above-described form (42) of the steering apparatus wherein theimpact energy absorbing member takes the form of a plate, theenergy-absorbing-load changing mechanism utilizes the impact energyabsorbing plate as a deformable member and the end portion of themounting portion as a forcing member for forcing the impact energyabsorbing plate so as to cause deformation of this plate, as in theabove-described form (41), so that the impact energy absorbing load ischanged by changing a state of engagement between the deformable memberand the forcing member. Unlike the energy-absorbing-load changingmechanism provided in the above form (41), the energy-absorbing-loadchanging mechanism provided in the present form (42) includes themovable member provided on the movable portion, and themovable-member-movement restricting mechanism for restricting themovement of the movable member, so that the impact energy absorbing loadis increased by a force of friction generated between the movable memberand the impact energy absorbing member. This energy-absorbing-loadchanging mechanism is also considered to employ a purely mechanicalmeans operable according to the principle of dynamics, which is highlyreliable in operation and simpler in construction and available at alower cost than an electrical means. The movable member includes notonly a linear movable member but also a rotatable member.

Best Mode for Carrying Out the Invention

There will be described some embodiments of the present invention, andsome modifications thereof, in the form of a steering apparatus for usein a motor vehicle, in particular, a shock absorbing steering apparatusof the type wherein a column holder structure is provided with an energyabsorbing plate. For convenience sake, the embodiments described beloware classified into several groups, and the embodiments andmodifications thereof of each group will be described in detail byreference to the accompanying drawings. It will be understood that thepresent invention is not limited to the following illustratedembodiments, and may be otherwise embodied with various changes,alterations and improvements, such as those described in the foregoingDETAILED DESCRIPTION OF THE INVENTION, which may occur to those skilledin the art. In the following descriptions, the same reference numeralswill be used in the different embodiments of the invention, to denotefunctionally identical or similar elements, where appropriate, andredundant description of those elements is avoided as much as possibleunless some redundancy is deemed necessary.

First Group of Embodiments

There will be described first through fifth embodiments of thisinvention, which are similar to each other and constitute the firstgroup of embodiments.

First Embodiment

i) Arrangement of Shock Absorbing Steering Apparatus of the FirstEmbodiment

Referring first to FIGS. 1-6, there is shown a shock absorbing steeringapparatus constructed according to a first embodiment of this invention.In this first embodiment, the steering apparatus includes a steeringshaft 10 having an upper shaft 11 and a lower shaft 12 which are axiallymovable relative to each other and rotatable together so as to transmita torque. Thus, the steering shaft 10 is contractible and extensible inthe axial direction. The steering shaft 10 is freely rotatably supportedby a steering tube 20 having an outer tube 21 and an inner tube 22 whichare axially movable relative to each other. Thus, the steering tube 20is also contractible and extensible in the axial direction. The steeringshaft 10 and the steering tube 20 cooperate to constitute a column body25. This column body 25 is assembled with respect to a body of a motorvehicle such that the column body 25 is inclined, with its right endportion (as seen in FIGS. 1 and 2) being located rearwardly and upwardlyof its left end portion.

The upper shaft 11 is freely rotatably supported by the outer tube 21via a bearing 13 such that the upper shaft 11 is not axially movablerelative to the outer tube 21. To the right end portion (as seen inFIG. 1) or upper end portion of the upper shaft 11, there is attached asteering wheel (not shown) provided with an air bag device, such thatthe steering wheel is rotatable with the upper shaft 11. On the otherhand, the lower shaft 12 is freely rotatably supported by the inner tube22 via a bearing 14, and is connected at its left end portion (as seenin FIG. 1) through a universal joint (not shown) to an intermediateshaft (not shown), which is axially contractible and extensible andcapable of transmitting a torque. The intermediate shaft is connectedthrough a universal joint to a steering gear box (not shown), as wellknown in the art.

The outer tube 21 is axially slidably fitted at its front or lower endportion on a rear or upper end portion of the inner tube 22, and isprovided at its lower end portion with a bracket 21 a and a rear supportmechanism A. The rear support mechanism A incorporates a tiltingmechanism for adjusting the angle of inclination or tilting of thesteering shaft 10, and a telescopic mechanism for adjusting the axiallength of the steering shaft 10. The outer tube 21 is fixed to abody-side bracket 31 (which may also be called “steering supportbracket”) via the bracket 21 a and the rear support mechanism A. Thebody-side bracket 31 is fixed to a portion of the vehicle body. On theother hand, the inner tube 22 is provided at its front or lower endportion with a bracket 22 a and a front support mechanism B, and ispivotally connected to another portion of the vehicle body via thebracket 22 a and the rear support mechanism B.

The rear support mechanism A includes a column holder structure in theform of a break-away bracket 41 arranged to support the bracket 21 afixed to the outer tube 21, such that the bracket 21 a is pivotable ortiltable in the vertical direction. The rear support mechanism A furtherincludes a tilting mechanism 35 arranged to lock and release the bracket21 a fixed to the outer tube 21, to and from the break-away bracket 41,and a telescopic mechanism 36 arranged to lock and release the outertube 21 to and from the inner tube 22.

The tilting mechanism 35 is constructed as well known in the art, and isoperable by a manually operated lever between a locking position and areleasing position. In the releasing position of the tilting mechanism35, the column body 25 is integrally tiltable relative to the break-awaybracket 41, in a vertical plane parallel to the longitudinal directionof the vehicle. The telescopic mechanism 36 is also constructed as wellknown in the art, and is operable by a manually operated lever between alocking position and a releasing position. In the releasing position ofthe telescopic mechanism 36, the upper shaft 11 and the outer tube 21are axially movable relative to the lower shaft 12 and the inner tube22, respectively, so as to permit adjustment of the axial length of thecolumn body 25.

The break-away bracket 41 has a pair of arms 41 a, 41 b extending in thelateral or transverse direction (direction of width) of the vehicle, andis fixed to the body-side bracket 31 by bolts 44 inserted through slots41 a 1, 41 b 1 formed in the respective arms 41 a, 41 b, viaintermediate members in the form of resin capsules 42 and metalliccollars 43, as shown in FIG. 5. Each bolt 44 is screwed into a nut 32fixed to the body-side bracket 31.

The slots 41 a 1 and 41 b 1 formed through the break-away bracket 41permit this break-away bracket 41 to be moved in the forward directionrelative to the body-side bracket 31 in the event of a secondarycollision of the vehicle operator (occupant or passenger) with thesteering wheel upon collision of the vehicle with a preceding vehicle,for example. As indicated by broken lines in FIG. 2, each of the slots41 a 1 and 41 b 1 is formed through a rear half of the corresponding arm41 a, 41 b, such that the slot extends from an almost central portion ofthe corresponding arm toward its rear or upper end and is open at therear end in the rearward direction (upward direction). As shown in FIG.5, each resin capsule 42 has a cylindrical portion 42 a fitted in thecorresponding slot 41 a 1, 41 b 1, and is bonded to the upper surface ofthe corresponding arm 41 a, 41 b. When an impact force acting on theresin capsule 42 exceeds a given threshold in the event of the secondarycollision, the resin capsule 42 is broken down or fractured. Eachmetallic collar 43 is press-fitted in the cylindrical portion 42 a ofthe corresponding resin capsule 42, and the bolt 44 is inserted throughthe metallic collar 43 and fixed to the body-side bracket 31. The impactforce acts on the resin capsule 42 through the bolt 44 and the metalliccollar 43.

The front support mechanism B is provided to pivotably support the innertube 22 of the steering tube 20, and includes a collar 51 freelyrotatably fitted in a fitting hole 22 a 1 formed through the bracket 22a fixed to the front or lower end portion of the inner tube 22. Thecollar 51 is fixed to a portion (not shown) of the vehicle body by abolt and a nut (both of which are not shown).

The shock absorbing steering apparatus constructed as described aboveincludes a steering column generally indicated at 5 in FIGS. 1 and 2.This steering column 5 includes: the column body 25 (steering shaft 10and steering tube 20); the rear support mechanism A including thebreak-away bracket 41, the tilting mechanism 35 and the telescopicmechanism 36; and the front support mechanism B including the bracket 22a.

The shock absorbing steering apparatus according to the present firstembodiment further includes an impact energy absorbing mechanism Cinterposed between the outer tube 21 and the inner tube 22, as shown inFIGS. 1 and 2. The impact energy absorbing mechanism C is provided toabsorb an impact energy generated in the event of a secondary collisionof the vehicle operator (occupant or passenger) with the steering wheelupon collision of the vehicle. The impact energy absorbing mechanism Cis arranged to permit the column body 25 to be axially contracted, forthereby absorbing the generated impact energy. To this end, the impactenergy absorbing mechanism C is provided with an energy absorbing member61.

The energy absorbing member 61 is deformable in a shearing or plasticdeformation mode as a result of axial contraction of the column body 25from its initial position of FIGS. 1 and 2 by more than a predeterminedaxial distance L1. The energy absorbing member 61 is formed of a resin,a light metal or a similar material and generally C-shaped in transversecross section. The energy absorbing member 61 is integrally fixed to theouter circumferential surface of the inner tube 22.

The energy absorbing member 61 includes a thin-walled support portion 61a which axially slidably supports the front portion of the outer tube21, and a plurality of ribs 61 b formed integrally on the outer surfaceof the support portion 61 a. The ribs 61 b undergo shearing or plasticdeformation by the front end portion of the outer tube 21 when thecolumn body 25 is axially contracted by more than the predeterminedaxial distance L1. As shown in FIG. 1, the energy absorbing member 61has a plurality of protrusions 61 c fixedly fitted in respective fittingholes 22 b formed in the inner tube 22. The protrusions 61 c are formedintegrally with an axially intermediate portion of the impact energyabsorbing member 61, so as to extend radially inwardly of the inner tube22.

Each of the ribs 61 b has a suitable amount of protrusion from the outersurface of the support portion 61 a in the radially outward direction ofthe inner tube 22, and has a suitable axial length. When the outer tube21 is axially moved from its initial position of FIGS. 1 and 2 relativeto the inner tube 22 in the forward and downward direction, by more thanthe predetermined axial distance L1, the ribs 61 b are deformed in theshearing or plastic deformation mode, thereby generating a suitableamount of impact energy absorbing load. The shape and number of the ribs61 b may be selected as needed. (*1) In the first embodiment shown inFIGS. 1-6, the break-away bracket 41 includes a main body portion havinga central portion 41 c which is located almost intermediate between thetwo arms 41 a, 41 b in the lateral direction of the vehicle. The centralportion 41 c consists of two plates 41 c 1 and 41 c 2 partiallysuperposed on each other, as shown in FIG. 3. The lower plate 41 c 2projects from the front end of the upper plate 41 c 1 by a suitabledistance in the axial direction of the column body 25. That is, thelower plate 41 c 2 includes a projecting front end portion 41 c 3, onwhich a guide member 49 formed of a resin is mounted. An impact energyabsorbing member in the form of an energy absorbing plate 71 is mountedon the central portion 41 c of the break-away bracket 41, with the guidemember 49 being interposed therebetween. In the present embodiment, thecentral portion 41 c of the break-away bracket 41 and the guide member49 attached to the projecting front end portion 41 c 3 of the centralportion 41 c cooperate to constitute a mounting portion 45 on which theimpact energy absorbing member in the form of the plate 71 is mounted.

The energy absorbing plate 71 is a single generally elongate metallicplate capable of functioning to absorb the impact energy generated inthe event of the secondary collision of the vehicle operator (orpassenger) with the steering column 5 (more precisely, with the steeringwheel) upon collision of the vehicle, such that the impact energy isabsorbed with a forward movement of the break-away bracket 41 relativeto the vehicle body, which takes place when the outer tube 21 of thecolumn body 25 is axially moved forward relative to the vehicle body bythe secondary collision. As shown in the enlarged views of FIGS. 3-6,the energy absorbing plate 71 includes a U-shaped portion 71 a held inengagement with the guide member 49 such that the U-shaped portion 71 ais displaceable relative to the break-away bracket 41. The energyabsorbing plate 71 further includes a T-shaped engaging portion 71 bformed at its upper rear end portion. The engaging portion 71 b isengageable with a holding portion 31 a formed on the body-side bracket31.

The U-shaped portion 71 a is fitted on the two plates 41 c 1 and 41 c 2of the break-away bracket 41 and the guide member 49 of the mountingportion 45, such that opposed two straight arms of the U-shaped portion71 a sandwich the two mutually superposed plates 41 c 1, 41 c 2 in thevertical direction, as shown in FIG. 3. The U-shaped portion 71 aincludes an arcuate curved section 71 a 1, and the above-indicated twostraight arms in the form of an upper arm section 71 a 2 and a lower armsection 71 a 3 which are connected together by the curved section 71 a1. The guide member 49 has a front portion held in contact with thecurved section 71 a 1, and functions as a guide portion 48 operable todeform the energy absorbing plate 71 along the curvature of the curvedsection 71 a 1, in pressing and sliding contact with the curved section71 a 1, when the outer tube 21 is axially moved relative to the vehiclebody in the event of the secondary collision indicated above. The guideportion 48 also functions as a forcing portion operable to force adeformable member in the form of the energy absorbing plate 71, so as tocause deformation of the deformable member.

The upper straight arm section 71 a 2 extends from the upper end of thecurved section 71 a 1 rearwardly of the steering column 5, and is heldin contact with the upper surface of the guide member 49 and the uppersurface of the upper plate 41 c 1 of the break-away bracket 41. However,the upper arm section 71 a 2 may be held in close proximity to the uppersurfaces indicated above. The upper arm section 71 a 2 terminates at itsrear end in the T-shaped engaging portion 71 b. On the other hand, thelower straight arm section 71 a 3 extends from the lower end of thecurved section 71 a 1 rearwardly, of the steering column 5, and is heldin contact with or in close proximity to the lower surface of the guidemember 49 and the lower surface of the lower plate 41 c 2 of thebreak-away bracket 41. When the break-away bracket 41 is moved forwardrelative to the vehicle body, the lower arm section 71 a 3 is forced bya semi-cylindrical portion 49 f of the guide member 49 in slidingcontact with the semi-cylindrical portion 49 f, and is plasticallydeformed along the curvature of the semi-cylindrical portion 49 f. Thissemi-cylindrical portion 49 f constitutes the guide portion 48 describedabove. This deformation of the lower arm section 71 a 3 results inabsorbing the impact energy generated upon the above-described secondarycollision, and a change in the longitudinal position of the energyabsorbing plate 71 in which the curved section 71 a 1 is formed.

The T-shaped engaging portion 71 b extends upwards from the rear end ofthe upper arm section 71 a 2 of the U-shaped portion 71 a. In otherwords, the T-shaped engaging portion 71 b is formed by bending the rearend section of the U-shaped portion 71 a 1 such that the T-shapedengaging portion 71 b is perpendicular to the upper arm section 71 a 2.The T-shaped engaging portion 71 b includes a pair of engaging pieces 71b 1 and 71 b 2 formed at its upper end, such that the engaging pieces 71b 1, 71 b 2 are engageable with the holding portion 31 a of thebody-side bracket 31 fixed to the vehicle body. Before the break-awaybracket 41 is moved forward relative to the vehicle body, the T-shapedengaging portion 71 b is rearwardly spaced by a predetermined distanceL2 from an engaging position (indicated by phantom line in FIGS. 1 and3) at which the T-shaped engaging portion 71 b engages the holdingportion 31 a of the body-side bracket 31. Thus, there is provided a freerunning distance L2 between the T-shaped engaging portion 71 b and theholding portion 31 a (more precisely, the front end of a recessed part31 a 1 of the holding portion 31 a), so that the break-away bracket 41and the energy absorbing plate 71 are freely movable relative to thebody-side bracket 31 by the free running distance L2 from the initialposition (before the movement). When the two engaging pieces 71 b 1, 71b 2 of the engaging portion 71 b are brought into engagement with theholding portion 31 a of the body-side bracket 31, the engaging pieces 71b, 71 b 2 are subjected to a shearing stress.

As indicated above, the holding portion 31 a of the body-side bracket 31has the recessed part 31 a 1, which is open at its rear end in therearward direction of the vehicle and with which the engaging portion 71b of the energy absorbing plate 71 is engageable. This recessed part 31a 1 has a cutout having a width slightly larger than a width W1 of anupright part of the T-shaped engaging portion 71 b. This cutout of therecessed part 31 a 1 functions as a guide for guiding a movement of theT-shaped engaging portion 71 b relative to the holding portion 31 a whenthe engaging portion 71 b is brought into engagement with the holdingportion 31 a. The upper surface of the recessed part 31 a 1 is inclinedin its rear end portion, to facilitate an initial action of engagementof the engaging portion 71 b with the recessed part 31 a 1. (*2)

In the present first embodiment, the arcuate curved section 71 a 1 ofthe U-shaped portion 71 a of the energy absorbing plate 71 has a smallerwidth than that of the other sections 71 a 2, 71 a 3, so that the impactenergy absorbing load increases at a relatively low rate in an initialperiod of engagement of the engaging portion 71 b with the holdingportion 31 a. Thus, the curved section 71 a 1 having the relativelysmaller width dimension serves as an initial-load adjusting mechanismarranged to adjust the impact energy absorbing load in the initialperiod of engagement of the engaging portion 71 b with the holdingportion 31 a.

The guide member 49 has a pair of upper positioning projections 49 a 1,49 a 2 which are spaced apart from each other in the direction of widthof the upper arm section 71 a 2, and a pair of upper positioning andholding pieces 49 b 1, 49 b 2 which are also spaced apart from eachother in the above-indicated direction of width, as shown, in FIG. 4.The upper positioning projections 49 a 1, 49 a 2 are formed in the frontend portion of the guide member 49, while the holding pieces 49 b 1, 49b 2 are formed in the rear end portion of the guide member 49. The upperarm section 71 a 2 of the energy absorbing plate 71 is positioned in arelatively front portion thereof by and between the two upperpositioning projections 49 a 1, 49 a 2 in the direction of width, and ina relatively rear portion thereof by and between the two upperpositioning and holding pieces 49 b 1, 49 b 2 in the direction of widthand in the direction of thickness. The front end portion of the lowerarm section 71 a 3 has a width which gradually increases in the rearwarddirection from its front end toward its rear end, so that the impactenergy absorbing load in the initial period of engagement of theengaging portion 71 b with the holding portion 31 a gradually increases.The guide member 49 further has a pair of lower positioning and holdingpieces 49 c 1, 49 c 2 which are spaced apart from each other in thedirection of width of the lower arm section 71 a 3, so that the lowerarm section 71 a 3 is positioned in a longitudinally intermediateportion thereof by and between the lower positioning and holding pieces49 c 1, 49 c 2 in the directions of width and thickness.

In the present first embodiment, the T-shaped engaging portion 71 b hasa length or height in the direction of thickness of the upper armsection 71 a 2, which is larger than a height of the upper positioningand holding pieces 49 b 1, 49 b 2 of the guide member 49. As shown inFIG. 4, the width W1 of the upright part of the T-shaped engagingportion 71 b is made smaller than a distance between the two upperpositioning and holding pieces 49 b 1, 49 b 2 of the guide member 49, sothat the upright part is movable between the two upper positioning andholding pieces 49 b 1, 49 b 2 in the axial direction of the steeringcolumn 5.

As shown in FIGS. 7-9, the guide member 49 is generally J-shaped as seenin the plane of FIG. 7, and has the above-described two upperpositioning projections 49 a 1, 49 a 2 and two upper positioning andholding pieces 49 b 1, 49 b 2 for positioning the upper arm section 71 a2 of the energy absorbing plate 71, and the above-described two lowerpositioning and holding pieces 49 c 1, 49 c 2 for positioning the lowerarm section 71 a 3 of the energy absorbing plate 71.

The guide member 49 has a recessed portion 49 d and an engagingprotrusion 49 e for engagement with the projecting front end portion 41c 3 of the break-away bracket 41, as shown in FIGS. 7-9, and theabove-described semi-cylindrical portion 49 f for plastically deformingthe lower arm section 71 a 3 of the energy absorbing plate 71. The guidemember 49 includes a rear extension 49 n extending along the lower plate41 c 2 of the break-away bracket 41, as shown in FIGS. 3 and 7, and theengaging protrusion 49 e is formed on the rear extension 49 n. The guidemember 49, which is thus generally J-shaped as seen in FIG. 7, ismounted on the break-away bracket 41 such that the rear end face of theshort upper arm on which the upper positioning projections 49 a 1, 49 a2 are formed is held opposed to the front end of the upper plate 41 c 1of the break-away bracket 41.

The two upper positioning and holding pieces 49 b 1, 49 b 2 are formedintegrally with the rear extension 49 n of the guide member 49, andextend through a through-hole 41 d formed through the break-away bracket41 such that the upper end portions of the upper positioning and holdingpieces 49 b 1, 49 b 2 are located adjacent to the respective oppositeside faces of the upper arm section 71 a 2 of the energy absorbing plate71. As shown in FIG. 9, the upper end portions of the two upperpositioning and holding pieces 49 b 1, 49 b 2 have respective slantsurfaces S1 and S2 which are formed such that a distance between thesetwo slant surfaces S1, S2 decreases in the upward direction in which theupper positioning and holding pieces 49 b 1, 49 b 2 extend from the rearextension 49 n, that is, in a direction from the lower arm section 71 a3 toward the upper arm section 71 a 2. The upper arm section 71 a 2 ofthe energy absorbing plate 71 is positioned in its directions of widthand thickness, between each of the slant surfaces S1, S2 and the uppersurface of the upper plate 41 c 1 of the break-away bracket 41.

The two lower positioning and holding pieces 49 c 1, 49 c 2 are alsoformed integrally with the rear extension 49 n of the guide member 49,such that the lower positioning and holding pieces 49 c 1, 49 c 2 arelocated adjacent to the respective opposite side faces of the lower armsection 71 a 3 of the energy absorbing plate 71. As also shown in FIG.9, the two lower positioning and holding pieces 49 c 1, 49 c 2 haverespective slant surfaces S3 and S4 which are formed such that adistance between these two slant surfaces S3, S4 decreases in thedownward direction in which the lower positioning and holding pieces 49c 1, 49 c 2 extend from the rear extension 49 n. The lower arm section71 a 3 of the energy absorbing plate 71 is positioned in its directionsof width and thickness, between each of the slant surfaces S3, S4 andthe lower surface of the rear extension 49 n of the guide member 49.

ii) Operation of Shock Absorbing Steering Apparatus of First Embodiment

In the shock absorbing steering apparatus according to the firstembodiment of the invention described above, the break-away bracket 41is moved and released from the body-side bracket 31 in the forwarddirection of the vehicle, with breakage of the resin capsules 42, in theevent of a secondary collision of the vehicle operator or occupant withthe steering wheel attached to the steering column 5, upon collision ofthe vehicle in question with any object such as a vehicle existing infront of the vehicle in question. As a result, a rear portion of thesteering column 5 (referred to as “movable portion” of the steeringcolumn 5, which includes the outer tube 21 of the column body 25, andthe break-away bracket 41 supporting the outer tube 21) is moved in theforward direction relative to the vehicle body. When the break-awaybracket 41 is moved in the forward direction together with the movableportion of the steering column 5, the T-shaped engaging portion 71 b ofthe energy absorbing plate 71 is brought into engagement with therecessed part 31 a 1 of the holding portion 31 a of the body-sidebracket 31.

After the engaging portion 71 b of the energy absorbing plate 71 hasbeen brought into engagement with the holding portion 31 a of thebody-side bracket 31, the break-away bracket 41 is further moved in theforward direction with the movable portion of the steering column 5, thestraight lower arm section 71 a 3 of the U-shaped portion 71 a of theenergy absorbing plate 71 is plastically deformed by and along thesemi-cylindrical portion 49 f of the guide member 49 mounted on thefront portion of the break-away bracket 49. In other words, the relativemovement of the energy absorbing plate 71 relative to the mountingportion 45 for mounting the energy absorbing plate 71 causes plasticdeformation of the lower arm section 71 a 3, so as to gradually changethe position of the curved section 71 a 1 of the U-shaped portion 71 ain the longitudinal direction of the energy absorbing plate 71.Described in greater detail, the front end portion of the instantlyformed straight lower arm section 71 a 3 adjacent to the instantlyformed curved section 71 a 1 is curved along the semi-cylindricalportion 49 f, while the upper end part of the instantly formed curvedsection 71 a 1 which is adjacent to the instantly formed straight upperarm section 71 a 2 is straightened to contribute to new formation of theupper arm section 71 a 2. The plastic deformation of the U-shapedportion 71 a of the energy absorbing plate 71 which takes place asdescribed above results in absorption of the impact energy generated bythe secondary collision of the vehicle occupant with the steering wheel.It is noted that the semi-cylindrical portion 49 f of the guide member49 which is held in pressing and sliding contact with the curved section71 a 1 of the U-shaped portion 71 a functions as the guide portion 48,which facilitates a change in the position of the curved section 71 a 1by plastic deformation of the U-shaped portion 71 a.

The column body 25 is axially contracted by more than the predetermineddistance L1 from the initial position shown in FIGS. 1 and 2. Describedin detail, the upper shaft 11 and the outer tube 21 are axially moved inthe forward direction relative to the inner tube 22, by more than thepredetermined distance L1, so that the ribs 61 b of the energy absorbingmember 61 undergo plastic or shearing deformation. This deformation ofthe ribs 61 b also contribute to absorption of the impact energygenerated by the secondary collision indicated above.

iii) Advantages of Shock Absorbing Steering Apparatus of FirstEmbodiment

The shock absorbing steering apparatus constructed according to thefirst embodiment has various structural features which provide variousadvantages, some of which will be described below:

-   -   [1] In the first embodiment, the energy absorbing plate 71 is        held by only the break-away bracket 41 fixed to the body-side        bracket 31, so that the energy absorbing plate 71 can be easily        mounted on the steering column 5, with a higher degree of        positioning accuracy of the energy absorbing plate 71 relative        to the vehicle body, than the energy absorbing plate provided in        the conventional shock absorbing steering apparatus described        above under the heading “BACKGROUND ART”. Accordingly, the        present shock absorbing steering apparatus suffers from a        reduced amount of variation in the energy absorbing        characteristic. The energy absorbing plate 71 is not required to        be fixed at its rear end to the column body 25, leading to        reduction in the cost of assembling of the steering apparatus.

[2] In the first embodiment, the break-away bracket 41 is fixed to thebody-side bracket 31, at its right and left arms 41 a, 41 b that arespaced from each other in the lateral direction of the vehicle, and theenergy absorbing plate 71 is mounted on the central portion 41 c of thebreak-away bracket 41. Namely, the central portion 41 c of thebreak-away bracket 41 is effectively utilized to hold the energyabsorbing plate 71.

[3] In the first embodiment, the break-away bracket 41 holds the columnbody 25 such that the axial length of the column body 25 is adjustableby the telescopic mechanism 36, and such that the column body 25 ispivotable or tiltable through the tilting mechanism 35. In thisarrangement, a tilting movement and an adjustment of the axial length ofthe column body 25 do not cause a movement of the break-away bracket 41holding the energy absorbing plate 71, so that the energy absorbingplate 71 is operable as intended, irrespective of the operating statesof the tilting mechanism 35 and the telescopic mechanism 36.

[4] In the first embodiment, the U-shaped portion 71 a of the energyabsorbing plate 71 includes the upper and lower arm sections 71 a 2, 71a 3 which sandwich the front portion of the break-away bracket 41 in thedirection of thickness of the break-away bracket 41, and furtherincludes the engaging portion 71 b which extends from the rear end ofthe upper arm section 71 a 2 in the direction of thickness of thebreak-away bracket 41. In this arrangement, the energy absorbing plate71 can be easily mounted on the break-away bracket 41, by fitting theU-shaped portion 71 a on the front portion of the break-away bracket 41,before the break-away bracket 41 is fixed to the body-side bracket 31.

[5] In the first embodiment, the impact energy generated by thesecondary collision of the vehicle occupant with the steering wheelattached to the steering column 5 can be absorbed by plastic deformationof the lower arm section 71 a 3 of the U-shaped portion 71 a of theenergy absorbing plate 71 by the guide portion 48 provided on thebreak-away bracket 41, in the process of a displacement of thebreak-away bracket 41 relative to the energy absorbing plate 71, whilethe engaging portion 71 b of the energy absorbing plate 71 is held inengagement with the holding portion 31 a of the body-side bracket 31,after the break-away bracket 41 is moved and released from the body-sidebracket 31 in the forward direction of the vehicle due to the secondarycollision. The preset shock absorbing steering apparatus capable of thusabsorbing the impact energy is relatively simple in construction with arelatively small number of components.

[6] The energy absorbing plate 71 used in the present first embodimentis a single elongate metallic strip, which is provided at its rear endwith the engaging portion 71 b which is engageable with the holdingportion 31 a of the body-side bracket 31, such that the engaging portion71 b receives a shearing load or stress. This arrangement makes itpossible to reduce the thickness and width dimensions of the engagingportion 71 b while maintaining required degrees of strength and rigidityof the engaging portion 71 b. The thickness of the energy absorbingplate 71 and the width dimensions of the U-shaped portion 71 a andengaging portion 71 b can be determined as needed for the energyabsorbing plate 71 to be able to exhibit the desired energy absorbingcharacteristic, while assuring the required strength and rigidity of theengaging portion 71 b.

[7] In the present first embodiment provided with the initial-loadadjusting mechanism, the impact energy absorbing load is increased at arelatively low rate in an initial period of engagement of the engagingportion 71 b with the holding portion 31 a, that is, in an initialperiod of absorption of the impact energy. Accordingly, the impactenergy can be smoothly absorbed, without an abrupt increase of theimpact energy absorbing load which would cause an accordingly largeimpact on the vehicle operator or occupant. While the initial-loadadjusting mechanism is provided on the energy absorbing plate 71 servingas the impact energy absorbing member in the first embodiment, it is notessential to provide the energy absorbing member with the initial-loadadjusting mechanism. That is, the initial-load adjusting mechanism maybe provided between the impact energy absorbing member and at least oneof the vehicle body and the break-away bracket 41, in addition to or inplace of the initial-load adjusting mechanism provided on the impactenergy absorbing member. This modification also applies to the otherembodiments described below.

[8] In the first embodiment, there is provided the free-running distanceL2 between the T-shaped engaging portion 71 b of the energy absorbingplate 71 and the holding portion 31 a of the body-side bracket 31, sothat the engaging portion 71 b is freely movable by this free-runningdistance L2 in the initial period of the secondary collision.Accordingly, the moment of generation of the impact energy absorbingload upon deformation of the U-shaped portion 71 a of the energyabsorbing plate 71 by the break-away bracket 41 is suitably delayed withrespect to the moment at which the break-away bracket 41 is releasedfrom the vehicle body (body-side bracket 31). Accordingly, the impactgenerated in the initial period of the secondary collision can be madesmaller in the present arrangement, than in an arrangement in which thedeformation of the energy absorbing plate 71 is initiated as soon as thebreak-away bracket 41 has been released from the vehicle body. It isalso noted that the moment at which the impact energy absorbing load isgenerated by deformation of the U-shaped portion 71 a of the energyabsorbing plate 71 by the break-away bracket 41 can be suitably adjustedas needed by adjusting the free-running distance L2.

[9] In the first embodiment wherein the holding portion 31 a of thebody-side bracket 31 has the recessed part 31 a 1 having a cutout openat its rear end, the engaging portion 71 b of the energy absorbing plate72 is engageable with this recessed part 31 a 1. The above-indicatedfree-running distance L2 is provided between the engaging portion 71 band the front end of the cutout of the recessed part 31 a 1. Thus, therecessed part 31 a 1 functions as guiding means for guiding a movementof the engaging portion 71 b relative to the holding portion 31 a, tothereby assure high stability of engagement of the engaging portion 71 bwith the holding portion 31 a, even in the presence of the free-runningdistance L2. In the presence of the recessed part 31 a 1, the provisionof the free-running distance L2 does not require the engaging portion 71b to be spaced a large distance apart from the holding portion 31 a inthe rearward direction of the vehicle.

[10] In the present first embodiment, the two plates 41 c 1, 41 c 2superposed on each other are used to constitute the mounting portion 45of the break-away bracket 41 on which the guide member 49 and theU-shaped energy absorbing plate 71 are mounted, that is, to constitutethe substantially central portion 41 c of the break-away bracket 41. Thelower plate 41 c 2 has the projecting front end portion 41 c 3 whichprojects a suitable distance from the front end of the upper plate 41 c1 in the forward direction and which receives a load via the guidemember 49 when the energy absorbing plate 71 is deformed in pressing andsliding contact with the guide member 49, to absorb the impact energy.This arrangement eliminates a need of bending the break-away bracket 41to form the projecting front end portion 41 c 3, leading to reduction inthe cost of manufacture of the break-away bracket 41.

[11] In the present embodiment wherein the projecting front end portion41 c 3 described above is provided by one of the two plates 41 c 1, 41 c2 which projects from the other plate in the forward direction, theprojecting front end portion 41 c 3 is suitably protected from beingbent due to a load received through the guide member 49, so that theenergy absorbing plate 71 can be deformed in the intended manner, inpressing and sliding contact with the guide member 49, for absorbing theimpact energy. Accordingly, the stability in the amount of absorption ofthe impact energy by deformation of the energy absorbing plate 71 can beimproved.

[12] In the present embodiment wherein the lower plate 41 c 2 has theprojecting front end portion 41 c 3 projecting from the front end of theupper plate 41 c 1, the generally J-shaped guide member 49 is mounted onthe projecting front end portion 41 c 3 such that the rear end face ofthe short upper arm of the J-shaped guide member 49 is held opposed tothe front end of the upper plate 41 c 1 of the break-away bracket 41. Inthis arrangement, the upper arm section 71 a 2 of the t-shaped energyabsorbing plate 71 can be displaced in contact with or in closeproximity to the upper surface of the upper plate 41 c 1, so that thedistance between the upper and lower arm sections 71 a 2, 71 a 3 of theenergy absorbing plate 71 can be reduced.

[13] In the first embodiment, the upper arm section 71 a 2 of theU-shaped energy absorbing plate 71 is positioned and held with respectto the break-away-bracket 41, by positioning and holding means includingthe pair of upper positioning projections 49 a 1, 49 a 2 and the pair ofupper positioning and holding pieces 49 b 1, 49 b 2 which are formedintegrally with the guide member 49. The positioning and holding meansassures stable engagement of the engaging portion 71 b of the energyabsorbing plate 71 with the holding portion 31 a of the body-sidebracket 31, with the upper arm section 71 a 2 being positioned relativeto the break-away bracket 41, when the break-away bracket 41 is axiallymoved relative to the body-side bracket 31. The stable engagement of theengaging portion 71 b with the holding portion 31 a is permitted even inthe presence of the free-running distance L2 between the holding portion31 a of the body-side bracket 31 and the T-shaped engaging portion 71 bformed integrally with the upper arm section 71 a 2 of the energyabsorbing plate 71.

[14] In the present first embodiment, the pair of upper positioning andholding pieces 49 b 1, 49 b 2 are formed integrally with the relativelylong lower arm of the J-shaped guide member 49, in the form of the rearextension 49 n extending in the rearward direction. In this arrangement,the upper arm section 71 a 2 of the U-shaped energy absorbing plate 71is positioned relative to the break-away bracket 41, at the rear end ofthe rear extension 49 n which is spaced a considerably large distancefrom the semi-cylindrical portion 49 f of the guide member 49 in therearward direction, so that the upper arm section 71 a 2 by the upperpositioning and holding pieces 49 b 1, 49 b 2 can be positioned withhigh accuracy relative to the break-away bracket 41.

[15] In the present embodiment, the pair of lower positioning andholding pieces 49 c 1, 49 c 2 for positioning the lower arm 71 a 3 ofthe U-shaped energy absorbing plate 71 are also formed integrally withthe rear extension 49 n of the J-shaped guide member 49. Namely, thelower positioning and holding pieces 49 c 1, 49 c 2 function as a lowerpositioning and holding portion provided on the rear extension 49 n ofthe guide member 49. The positioning and holding means 49 a 1, 49 a 2,49 b 1, 49 b 2 and the holding portion 49 c 1, 49 c 2 constitute acompact positioning structure for positioning the upper and lower armsections 71 a 2, 71 a 3 of the U-shaped energy absorbing plate 71, so asto assure a high degree of accuracy of positioning of the energyabsorbing plate 71 relative to the break-away bracket 41 in thedirections of width and thickness of the plate 71.

[16] In the first embodiment, the upper end portions of the upperpositioning and holding pieces 49 b 1, 49 b 2 formed on the rearextension 49 n of the guide member 49 have the opposed slant, surfacesS1 and S2 which are formed such that the distance between these slantsurfaces S1, S2 decreases in the upward direction. The upper positioningand holding pieces 49 b 1, 49 b 2 having the slant surfaces S1, S2permit accurate positioning of the energy absorbing plate 71,irrespective of the specific thickness and width dimensions of theenergy absorbing plate 71 which are selected to adjust the desiredamount of absorption of the impact energy, as indicated in FIG. 10. Thisadvantage is also provided by the lower positioning and holding pieces49 c 1, 49 c 2 which are also formed on the rear extension of the guidemember 49 and which have the opposed slant surfaces S3 and S4 formedsuch that the distance between these slant surfaces S3, S4 decreases inthe downward direction, as shown in FIG. 9.

[17] In the present first embodiment, the width W1 of the upright partof the T-shaped engaging portion 71 b of the energy absorbing plate 71is made smaller than a distance W2 between the two upper positioning andholding pieces 49 b 1, 49 b 2 of the guide member 49, so that theupright part of the engaging portion 71 b is movable between the upperpositioning and holding pieces 49 b 1, 49 b 2 in the direction ofmovement of the break-away bracket 41 relative to the body-side bracket31. This dimensional relationship between the width W1 of the uprightportion of the engaging portion 71 b and the distance W2 between theupper positioning and holding pieces 49 b 1, 49 b 2 permits easymounting of the energy absorbing plate 71 on the break-away bracket 41with the guide member 49 attached thereto, by moving the U-shaped energyabsorbing plate 71 in the rearward direction relative to the break-awaybracket 41, with the upright portion of the T-shaped engaging portion 71b being passed between the two upper positioning and holding pieces 49 b1, 49 b 2.

iv) Modification of Shock Absorbing Steering Apparatus of FirstEmbodiment.

The energy absorbing plate 71 is mounted on the break-away bracket 41and the guide member 49, such that the upper arm section 71 a 2 issupported at its front end portion by the upper surfaces of the guidemember 49 and the upper plate 41 c 1 of the break-away bracket 41, andis positioned at its rear end portion by the upper positioning andholding pieces 49 b 1, 49 b 2 of the guide member 49, as shown in FIG.3. Namely, the upper arm section 71 a 2 is supported at its lowersurface by a portion of the mounting portion 45 of the break-awaybracket 41. However, this arrangement to support the upper arm section71 a 2 of the energy absorbing plate 71 may be modified, as shown inFIG. 11. In this modification, the upper arm section 71 a 2 is supportedat its front end portion by the upper surfaces of the guide member 49and the upper plate 41 c 1, at its intermediate portion by the upperpositioning and holding pieces 49 b 1, 49 b 2 of the guide member 49,and at its rear end portion by the upper surface of the upper plate 41 c1. In this modification, too, the upper arm section 71 a 2 is supportedat its lower surface by a portion of the mounting portion 45 of thebreak-away bracket 41. However, the upper positioning and holding pieces49 b 1, 49 b 2 for positioning the upper arm section 71 a 2 at itsintermediate portion cooperate with the guide member 49 and the upperplate 41c1 for supporting the upper arm section 71 a 2 at its front andrear end portions, to position the upper arm section 71 a 2 in itsdirection of thickness, with higher accuracy relative to the break-awaybracket 41, while holding the upper arm section 71 a 2 against thebreak-away bracket 41 with a sufficiently large force.

Second Embodiment

In the first embodiment, the upper arm section 71 a 2 of the U-shapedenergy absorbing plate 71 is positioned by the pair of upper holdingpieces 49 b 1, 49 b 2 of the guide member 49, as shown in FIG. 3. In asecond embodiment shown in FIG. 12, however, the upper arm section 71 a2 is supported by positioning and holding means in the form of arectangular three-sided clip 81. In the other aspects, the shockabsorbing apparatus according to the present second embodiment isidentical in construction and operation with that of the firstembodiment described above, and the second embodiment has the advantages[1] through [13] described above with respect to the first embodiment.

The rectangular three-sided clip 81 is formed from a metallic sheet intoa structure having three sides consisting of one side in the form of anelastically deformable intermediate curved section 81 a, and two opposedsides connected by the curved section 81 a, as shown in FIG. 13. Thecurved section 81 a is curved toward the interior space defined by thethree sides, and has a convex inner surface for elastically contactingthe upper surface of the upper arm section 71 a 2 of the energyabsorbing plate 71. The two opposed sides of the three-sided clip 81have respective elastically deformable engaging jaws 81 b forelastically contacting the lower surface of the lower arm section 71 a 3of the energy absorbing plate 71. The curved section 81 a and engagingjaws 81 b cooperate to constitute an elastically deformable portion forelastically engaging the upper and lower arm sections 71 a 2, 71 a 3 ofthe plate 71. The rectangular three-sided clip 81 is assembled withrespect to the break-away bracket 41, and the guide member 49 and theenergy absorbing plate 71 which have been mounted on the central portion41 c of the break-away bracket 41. The break-away bracket 41 has athrough-hole 41 d, so that the three-sided clip 81 can be insertedthrough the through-hole 41 d in the direction from the upper armsection 71 a 2 toward the lower arm section 71 a 3, so as to hold theupper and lower arm sections 71 a 2, 71 a 3 in elastically pressingcontact with the curved section 81 a and the upper ends of the engagingjaws 81 b, as shown in FIG. 12. The three-sided clip 81 can be releasedfrom the energy absorbing plate 71 when the energy absorbing plate 71 isdisplaced after the T-shaped engaging portion 71 b is brought intoengagement with the holding portion 31 a of the body-side bracket 31.

As also shown in FIG. 12, the guide member 49 includes a supportprojection 49 g formed on the rear extension 49 n. The curved section 81a and the engaging jaws 81 b of the rectangular three-sided clip 81force the upper arm section 71 a 2 against the upper surface of theupper plate 41 c 1 of the break-away bracket 41 and the upper surface ofthe support projection 49 g of the guide member 49, and forces the lowerarm section 71 a 3 against the lower surface of the rear extension 49 ofthe guide member 49. Thus, the guide member 49 and the energy absorbingplate 71 are assembled with respect to the central portion 41 c of thebreak-away bracket 41 in pressing contact with each other. In thissecond embodiment, the guide member 49, more specifically, the supportprojection 49 g functions as a supporting portion of the mountingportion 45, which cooperates with the three-sided clip 81 to function toelastically hold therebetween the upper arm section 71 a 2 of the energyabsorbing plate 71 in pressing contact therewith in the direction ofthickness of the upper arm section 71 a 2.

In the present second embodiment, the upper and lower arm sections 71 a2 and 71 a 3 of the energy absorbing plate 71 are elastically positionedand held by and between the rectangular three-sided clip 81 in thedirection of thickness of the arm sections. Thus, the energy absorbingplate 71 is mounted on the break-away bracket 41 without a risk ofrattling movements of the energy absorbing plate 71 relative to thebreak-away bracket 41. The second embodiment is also advantageous inthat the thickness of the energy absorbing plate 71 can be selectedwithin a certain range corresponding to a maximum amount of elasticdeformation of the curved section 81 a of the clip 81, without having tochange the configuration of the clip 81. Thus, the present embodiment iseffective where the amount of impact energy that can be absorbed by theenergy absorbing plate 71 is adjusted by suitably tuning the thicknessof the energy absorbing plate 71. Further, the impact energy generatedby the secondary collision described above can be absorbed in theintended manner, by the elastic deformation of the energy absorbingplate 71, owing to the automatic releasing of the three-sided clip 81from the energy absorbing plate 71 when the plate 71 is displacedrelative to the break-away bracket 41 after the T-shaped engagingportion 71 b is brought into engagement with the holding portion 31 a ofthe body-side bracket 31.

Referring next to FIG. 14, there is shown a modification of the secondembodiment, wherein the lower arm section 71a 3 of the energy absorbingplate 71 is partially curved at its intermediate portion in thedirection away from the lower surface of the rear extension 49 n of theguide member 49. This curved intermediate portion of the lower armsection 71 a 3 is elastically deformable and is held in elasticallypressing contact at its lower surface with the engaging jaws 81 b of thethree-sided clip 81. In this modification of FIG. 14, the thickness ofthe energy absorbing plate 71 can be selected within a range wider thanthat in the second embodiment.

Third Embodiment

A third embodiment of this invention is shown in FIG. 15. In this thirdembodiment, the upper arm section 71 a 2 of the energy absorbing plate71 is positioned and held with respect to the break-away bracket 41 bypositioning and means in the form of a holding band 91. In the otheraspects, the third embodiment is identical in construction and operationwith the first embodiment, and has the advantages [1] through [13]described above with respect to the first embodiment.

The holding band 91 is variable in its effective length of holding, andis arranged to hold together the upper arm section 71 a 2 of the energyabsorbing plate 71 and a support piece 41 c 1 a formed on the upperplate 41 c 1 of the break-away bracket 41. This support piece 41 c 1 afunctions as the supporting portion provided on the mounting portion 45.The holding band 91 is broken down or fractured when a load larger thana predetermined threshold acts on the holding band 91. That is, theholding band 91 is broken down when the energy absorbing plate 71 isdisplaced relative to the break-away bracket 41 after the T-shapedengaging portion 71 b is brought into engagement with the holdingportion 30 a of the body-side bracket 31.

In the present third embodiment, the thickness and width of the energyabsorbing plate 71 can be selected within relatively wide ranges,without having to change the configuration of the holding band 91, sincethe holding band 91 is capable of positioning and holding the upper armsection 71 a 2 of the energy absorbing plate 71 with respect to thebreak-away bracket 41, irrespective of the specific thickness and widthof the plate 71 within the above-indicated ranges. In this respect, thecost of manufacture of the present steering apparatus can be reduced.Further, the impact energy can be absorbed in the intended manner byelastic deformation of the energy absorbing plate 71 in pressing andsliding contact with the guide member 49, since the holder band 91 isautomatically broken down when the plate 71 is displaced relative to thebreak-away bracket 41 after the engaging portion 71 b is brought intoengagement with the holding portion 31 a of the body-side bracket 31.

Referring to FIGS. 16 and FIGS. 17A and 17B, there is shown a firstmodification of the third embodiment of the invention, wherein the rearextension 49 n of the guide member 49 has an attaching hole 49 h throughwhich the holding band 91 is inserted. In this modification, the holdingband 91 is prevented from being removed away from the support piece 41 c1 a of the upper plate 41 c 1 of the break-away bracket 41, in therearward direction, and is operable to achieve the intended positioningand holding function with high stability.

FIG. 18 shows a second modification of the third embodiment, wherein theholding band 91 is formed integrally with the rear extension 49 n of theguide member 49, such that the holding band 91 is adjustable in itsholding force and broken down when a load acting thereon exceeds a giventhreshold. In this modification, the costs of manufacture and assemblingof the steering apparatus can be reduced owing to the holding band 91integral with the guide member 49.

FIG. 19 shows a third modification of the third embodiment, wherein thelengths of the upper arm section 71 a 2 of the energy absorbing plate 71and the rear extension 49 n of the guide member 49 are determined suchthat the rear ends of the upper arm section 71 a 2 and the rearextension 49 n are located on the rear side of the through-hole 41 dformed through the break-away bracket 41. The upper and lower armsections 71 a 2 and 71 a 3 of the energy absorbing plate 71 and the rearextension 49 n are held together by the holding band 91, which is alsoadjustable in its holding force and broken down when the load acting onthe holding band 91 exceeds the threshold. In this modification, theholding band 91 prevents rattling movements of the energy absorbingplate 71 relative to the break-away bracket 41. In this modification,the upper plate 41 c 1 of the break-away bracket 41 functions as thesupporting portion.

FIG. 20 shows a fourth modification of the third embodiment, wherein therear end of the upper arm section 71 a 2 of the energy absorbing plate71 is not located on the rear side of the through-hole 41 d of thebreak-away bracket 41, while the rear end of the rear extension 49 n ofthe guide member 49 is located on the rear side of the through-hole 41d. Further, the support projection 49 g is formed integrally with therear extension 49 n. In this modification, the upper and lower armsections 71 a 2, 71 a 3, and the rear extension 49 n and supportprojection 49 g of the guide member 49 are held together by the holdingband 91, which is also adjustable in its holding force and broken downwhen the load acting on the holding band 91 exceeds the threshold. Inthis modification, too, the holding band 91 prevents rattling movementsof the energy absorbing plate 71 relative to the break-away bracket 41.

Fourth Embodiment

Referring next to FIG. 21, there is shown a fourth embodiment of thisinvention, wherein the upper arm section 71 a 2 of the energy absorbingplate 71 has U-shaped bent holding parts 71 c formed at its rear end.The bent holding parts 71 c function as the positioning and holdingmeans for positioning and holding the energy absorbing plate 71 withrespect to the break-away bracket 41. The bent holding parts 71 c gripthe rear end of the upper plate 41 c 1 of the break-away bracket 41, andis elastically deformable so that the bent holding parts 71 c arereleased from the upper plate 41 c 1 when the energy absorbing plate 71is displaced relative to the break-away bracket 41 after the engagingportion 71 b is brought into engagement with the holding portion 31 a ofthe body-side bracket 31. In the other aspects, the shock absorbingsteering apparatus according to the present fourth embodiment isidentical in construction and operation with the first embodiment, andthe fourth embodiment has the advantages [1] through [13] describedabove with respect to the first embodiment.

In the fourth embodiment wherein the upper arm section 71 a 2 of theenergy absorbing plate 71 includes the U-shaped bent holding parts 71 c,the energy absorbing plate 71 can be positioned and held with respect tothe break-away bracket 41, by simply designing the bent holding parts 71c depending upon the specific thickness and width of the energyabsorbing plate 71. Further, the impact energy can be absorbed in theintended manner by elastic deformation of the energy absorbing plate 71in pressing and sliding contact with the guide member 49, since the bentholding parts 71 c are automatically broken down when the plate 71 isdisplaced relative to the break-away bracket 41 after the engagingportion 71 b is brought into engagement with the holding portion 31 a ofthe body-side bracket 31.

Fifth Embodiment

Referring to FIGS. 22-25, there is shown a fifth embodiment of thisinvention, wherein the central portion 41 c of the break-away bracket 41is constituted by the two plates 41 c 1, 41 c 2, as in the firstembodiment, and a laterally central part of the front end portion of thelower plate 41 c 2 extends a suitable distance from the front end of theupper plate 41 c 1 in the forward direction, as the projecting front endportion 41 c 3. The guide member 49 formed of a resin material ismounted on this projecting front end portion 41 c 3.

In the fifth embodiment, the guide member 49 mounted on the projectingfront end portion 41 c 3 of the lower plate 41 c 2 is positioned by andbetween a pair of positioning projections 41 c 4 and 41 c 5 formed onthe upper plate 41 c 1, in the direction of width. These positioningprojections 41 c 4, 41 c 5 prevent rattling movements of the guidemember 49 relative to the break-away bracket 41 in the direction ofwidth of the energy absorbing plate 71.

In the fifth embodiment, the guide member 49 includes the positioningand holding means in the form of the pair of upper positioningprojections 49 a 1, 49 a 2 and the pair of upper positioning and holdingpieces 49 b 1, 49 b 2, the holding portion in the form of the lowerpositioning and holding pieces 49 c 1, 49 c 2, the recessed portion 49d, the engaging protrusion 49 e, the guide portion 48 in the form of thesemi-cylindrical portion 49 f, and the rear extension 49 n, as in thefirst embodiment. In the fifth embodiment, the upper positioningprojections 49 a 1, 49 a 2 extend from the semi-cylindrical portion 49 fby a larger distance in the forward direction than in the firstembodiment. In the fifth embodiment, the guide member 49 furtherincludes a pair of engaging jaws 49 i 1 and 49 i 2 spaced apart fromeach other in the direction of width, and a pair of protrusions 49 j 1and 49 j 2 spaced apart from each other in the direction of width.

The two engaging jaws 49 i 1, 49 i 2 are formed integrally with the twoupper positioning and holding pieces 49 b 1, 49 b 2 such that theengaging jaws 49 i 1, 49 i 2 extend from the upper positioning andholding pieces 49 b 1, 49 b 2 in the forward direction. The engagingjaws 49 i 1, 49 i 2 are held in engagement with respective recesses 71 d1, 71 d 2 formed in the upper arm section 71 a 2 of the U-shaped energyabsorbing plate 71, so that the removal of the energy absorbing plate 71from the guide member 49 in the forward direction is prevented.

The two protrusions 49 j 1, 49 j 2 are formed integrally with the rearextension 49 n of the guide member 49, such that the two protrusions 49j 1, 19 j 2 are located below the respective engaging jaws 49 i 1, 49 i2, in order to prevent an excessive amount of downward deformation orbending of the engaging jaws 49 i 1, 49 i 2 and consequent breakage orfracture of the engaging jaws 49 i 1, 49 i 2, when the guide member 49is mounted on the break-away bracket 41 or when the energy absorbingplate 71 is mounted on the guide member 49, with a backward movement ofthe plate 71 relative to the guide member 49.

In the present fifth embodiment, the two upper positioning and holdingpieces 49 b 1, 49 b 2 are bent laterally outwardly of the guide member49 when the energy absorbing plate 71 is mounted on the guide member 49with the rearward movement of the plate 71, as shown in FIG. 25, so thatthe upper positioning and holding pieces 49 b 1, 49 b 2 are brought intoabutting contact with the wall surfaces of the through-hole 41 d. Thus,the upper positioning and holding pieces 49 b 1, 49 b 2 prevent rattlingmovements of the guide member 49 relative to the break-away bracket 41in the direction of width of the guide member 49.

While the elements of the shock absorbing steering apparatus which arecharacteristic of the fifth embodiment have been described, the presentsteering apparatus is identical in construction and operation with thefirst embodiment, in the other aspects. The fifth embodiment has theadvantages [1] through [17] described above with respect to the firstembodiment.

Although the pair of engaging jaws 49 i 1, 49 i 2 provided in the fifthembodiment are formed so as to extend from the respective upperpositioning and holding pieces 49 b 1, 49 b 2 in the forward direction,the engaging jaws 49 i 1, 49 i 2 may be formed independently of theupper positioning and holding pieces 49 b 1, 49 b 2, as in a firstmodification of the fifth embodiment shown in FIGS. 26 and 27. In thismodification, the engaging jaws 49 i 1, 49 i 2 are bent downwardstowards respective protrusions 49 j 1 and 49 j 2 also formed on the rearextension 49 n of the guide member 49.

In the fifth embodiment, the removal of the U-shaped energy absorbingplate 71 in the forward direction is prevented by engagement of the twoengaging jaws 49 1 1, 49 i 2 with the respective two recesses 71 d 1, 71d 2 formed in the upper arm section 71 a 2 of the energy absorbing plate71. However, the removal of the energy absorbing plate 71 may bepresented by an arrangement in a second modification of the fifthembodiment shown in FIGS. 28 and 29, or an arrangement in a thirdmodification of the fifth embodiment shown in FIG. 30.

In the second modification of the fifth embodiment shown in FIGS. 28 and29, the two engaging jaws 49 i 1, 49 i 2 are replaced by a pair ofengaging projections 49 k 1 and 49 k 2 which are formed integrally withthe respective slant surfaces S1 and S2 of the upper positioning andholding pieces 49 b 1, 49 b 2. These engaging projections 49 k 1 and 49k 2 are held in engagement with the respective recesses 71 d 1, 71 d 2formed in the upper arm section 71 a 2 of the energy engaging plate 71which has been mounted on the guide member 49. Thus, the engagingprojections 49 k 1, 49 k 2 cooperate with the recesses 71 d 1, 71 d 2 toprevent the removal of the energy absorbing plate in the forwarddirection.

In the third modification of the fifth embodiment shown in FIG. 30, thetwo engaging jaws 49 i 1, 49 i 2 are replaced by a pair of engagingprojections 49 m 1 and 49 m 2 which are formed integrally with therespective opposed surfaces of the upper positioning projections 49 a 1,49 a 2. These engaging projections 49 m 1 and 49 m 2 are held inengagement with the respective recesses 71 d 1, 71 d 2 of the energyabsorbing plate 71 mounted on the guide member 49. Thus, the engagingprojections 49 m 1, 49 m 2 cooperate with the recesses 71 d 1, 71 d 2 toprevent the removal of the energy absorbing plate 71 in the forwarddirection.

Common Modifications of First Group of Embodiments

In the first through fifth embodiments described above, the positioningand holding means is provided in the steering apparatus of the typewhich has the free-running distance L2 in the axial direction betweenthe engaging portion 71 b formed integrally with the upper arm section71 a 2 of the U-shaped energy absorbing plate 71 and the holding portion31 a of the body-side bracket 31. However, positioning and holding meansmay be provided in a steering apparatus of the type in which theengaging portion of the energy absorbing plate is brought intoengagement with a holding portion provided on the vehicle body toprovisionally hold the energy absorbing plate when the break-awaybracket is mounted on a portion of the vehicle body. In the first groupof embodiments, the upper arm section of the energy absorbing plate ispositioned and held by the positioning and holding means with respect tothe break-away bracket, so that the break-away bracket can be easilyassembled with respect to the vehicle body (by screwing the bolts 44into the nuts 32, as shown in FIG. 5), with a high degree of accuracy ofpositioning of the upper arm section of the energy absorbing platerelative to the break-away bracket.

In each of the first and fifth embodiments, the column body 245 issupported by a portion of the vehicle body through the rear supportmechanism A and the front support mechanism B. However, a single supportmechanism may be provided for supporting the column body by the vehiclebody.

The shock absorbing steering apparatus according to each of the firstthrough fifth embodiments is arranged such that the impact energygenerated by the secondary collision of the vehicle operator or occupantcan be absorbed by not only the deformation of the energy absorbingplate 71 in pressing and sliding contact with the guide member 49, butalso the impact energy absorbing mechanism A provided on the column body25. However, an impact energy absorbing mechanism of the type other thanthat of the impact energy absorbing mechanism C may be provided betweenthe steering column 5 and the vehicle body. It is also noted that theprovision of the impact energy absorbing mechanism C is not essential,and may be eliminated.

The above-described common modifications of the first group ofembodiments are applicable to the other groups of embodiments which willbe described.

Second Group of Embodiment

There will be described sixth through eighth embodiments of thisinvention, which are similar to each other and constitute the secondgroup of embodiments.

Sixth Embodiment

Referring to FIGS. 31-35, there is shown a shock absorbing steeringapparatus constructed according to a sixth embodiment of the presentinvention. The steering column 5 and the other elements of this steeringapparatus are similar in construction with the first embodiment. Theforegoing description of the first embodiment from the beginning up tothe portion indicated by (*2), by reference to FIGS. 1-6, applies to thesteering apparatus of this sixth embodiment. In the followingdescription of the sixth embodiment and FIGS. 31-35, however, referencenumerals 131, 141, 149 and 171 are respectively used to denote thebody-side bracket, the break-away bracket, the guide member and theenergy absorbing plate, which are denoted by respective referencenumerals 31, 41, 49 and 71 in the first embodiment. Constituent parts ofthose elements 131, 141, 149 and 171 in the sixth embodiment are denotedby combinations of those reference numerals and alphabetic letters “a”,“b”, etc.

In the present sixth embodiment, the arcuate curved section 171 a 1 andthe upper arm in the form of the upper arm section 171 a 2 of theU-shaped energy absorbing plate 171 have a smaller width than the lowerarm in the form of the lower arm section 171 a 3, so that the impactenergy absorbing load is increased at a relatively low rate in theinitial period of engagement of the engaging portion 171 b with theholding portion 131 a of the body-side bracket 131, and increased to adesired value at a suitable point of time in the process of theengagement. Namely, the width of the curved section 171 a 1 is madesmaller than that of the lower arm section 171 a 3, and this dimensionalrelationship provides an initial-load adjusting mechanism.

The guide member 149 provided in this sixth embodiment has a recessedportion 149 d engaging the projecting front end portion 141 c 3 of thelower plate 141 c 2 of the break-away bracket 131, and includes anarcuate semi-cylindrical portion 149 f for plastically deforming thelower arm section 171 a 3 of the energy absorbing plate 171 in pressingand sliding contact therewith. As shown in FIG. 34, the guide member 149is a generally J-shaped structure including a rear extension 149 n whichextends from the lower portion in the backward direction of the vehicle,so as to form a relatively long arm of the J-shape. The guide member 149is mounted on the break-away bracket 141 such that the rear end face ofa relatively short arm of the J-shape is opposed to the front end faceof the upper plate 141 c. The rear extension 149 n is formed with a hookportion 149 e at its rear end. This hook portion 149 e is held inengagement with the rear end portion of the lower plate 141 c 2 of thebreak-away bracket 141, as shown in FIG. 34.

In the present shock absorbing steering apparatus, the break-awaybracket 141 is moved and released from the body-side bracket 131 in theforward direction of the vehicle, with the breakage of the resincapsules 42 when an impact acting on the resin capsules 42 exceeds apredetermined upper limit in the event of a secondary collision of thevehicle operator or occupant upon collision of the vehicle with anyobject. As a result of the forward movement of the break-away bracket141, the engaging portion 171 b of the energy absorbing plate 171mounted on the moving break-away bracket 141 is eventually brought intoengagement with the holding portion 131 a of the body-side bracket 131.

With a further forward movement of the break-away bracket 141 relativeto the vehicle body after the engagement of the engaging portion 171 bof the energy absorbing plate 171 with the holding portion 131 a of thebody-side bracket 131, the lower arm section 171 a 3 of the U-shapedportion 171 a of the energy absorbing plate 171 is deformed by and alongthe semi-cylindrical section 149 f of the guide member 149, in pressingand sliding contact with the arcuate surface of the semi-cylindricalportion 149 f. Accordingly, the position of the instantly formed curvedsection 171 a 1 of the U-shaped portion 171 a in the longitudinaldirection of the energy absorbing plate 171 is gradually shifted whilethe instantly formed upper and lower arm sections 171 a 2 and 171 a 3are moved in sliding contact with the upper plate 141 c and the rearextension 149 n of the guide member 149. Thus, the impact energy can beabsorbed by deformation of the energy absorbing plate 171 in pressingand sliding contact with the guide member 149.

The column body 25 is axially contracted by more than the predetermineddistance L1 from the initial state indicated in FIGS. 31 and 32.Described in detail, the upper shaft 11 and the outer tube 21 areaxially moved in the forward direction relative to the lower shaft 12and the inner tube 22 by more than the predetermined distance L1, sothat the ribs 61 b of the energy absorbing member 61 are deformed in ashearing or plastic deformation mode, and the impact energy is alsoabsorbed by the shearing or plastic deformation of the ribs 61 b.

In the present sixth embodiment, positioning and holding means is notprovided for positioning and holding the upper arm section 171 a 2 ofthe energy absorbing plate 171. However, the steering apparatus of thepresent embodiment has the advantages [1] through [12] described abovewith respect to the first embodiment. However, the positioning andholding means may be provided in this embodiment, as described above.

While the steering apparatus of the sixth embodiment described aboveuses the energy absorbing plate 171 shown in FIGS. 31-35 and thebody-side bracket 131 having the holding portion 131 a, a modifiedenergy absorbing plate 171 may be employed, as in a first modificationof the sixth embodiment shown in FIG. 36, and a modified body-sidebracket 131 may be employed, as in a second modification of the sixthembodiment shown in FIG. 37. In the energy absorbing plate 171 shown inFIG. 36, the T-shaped engaging portion 171 b has an upper section whichis bent to be L-shaped in cross section, so that the engaging portion171 b has an increased mechanical strength. In the body-side bracket 131shown in FIG. 37, the rear end portion in which the holding portion 131a is formed is bent downwardly to increase its mechanical strength.

Further, a modified body-side bracket 132 may be used as in a thirdmodification of the sixth embodiment shown in FIG. 38. This modifiedbody-side bracket 132 includes a holding portion 132 a which does nothave a cutout. This third modification uses a modified energy absorbingplate 172 including a pair of hooked engaging portions 172 b in place ofthe T-shaped engaging portion 171 b. The hooked engaging portions 172 bare engageable with the holding portion 132 a not having the cutout. Ina fourth modification of the sixth embodiment shown in FIG. 39, theenergy absorbing plate 172 of FIG. 38 is replaced by an energy absorbingplate 172 which includes an engaging portion in the form of has a pairof L-shaped bent portions 172 c engageable with the holding portion 132a. Each bent portion 172 c is L-shaped in cross section in a plane whichis parallel to the direction of width of the plate 172 and perpendicularto the plane of the plate 172.

Further, a modified body-side bracket 133 may be used as in a fifthmodification of the sixth embodiment shown in FIG. 40. This modifiedbody-side bracket 133 includes a holding portion in the form of anengaging protrusion 133 a extending in the rearward direction. Thisfifth modification uses a modified energy absorbing plate 173 includingan engaging portion 173 b which has an engaging hole. 173 b 1 engageablewith the engaging protrusion 133 a.

Seventh Embodiment

Referring next to FIGS. 41-43, there is shown a shock absorbing steeringapparatus constructed according to a seventh embodiment of thisinvention. In this seventh embodiment, the body-side bracket 131 isprovided with a load changeover device 180. The seventh embodiment issubstantially identical in construction with the sixth embodiment ofFIGS. 31-35, except for the load changeover device 180, and has not onlythe same advantages as those of the sixth embodiment, but alsoadditional advantages owing to the provision of the load changeoverdevice 180, which will be described.

The load changeover device 180 is an engagement adjusting mechanismarranged to permit or inhibit the engagement of the T-shaped engagingportion 171 b of the energy absorbing plate 171 with the holding portion131 a of the body-side bracket 131. The load changeover device 180includes an opening and closing plate 181 mounted on the body-sidebracket 131, and an electromagnetic actuator 182 arranged to selectivelypermit and inhibit a movement of the opening and closing plate 181 inthe forward direction of the vehicle.

The opening and closing plate 181 is mounted on the body-side bracket131 via a holder 134 fixed to the bracket 131, such that the plate 181is movable relative to the bracket 131 in the longitudinal direction ofthe vehicle, to selectively open and close the recessed part 131 a 1.The opening and closing plate 181 has a central through-hole 181 a inwhich a cylindrical portion 184 a of a resin collar 184 is fitted, asshown in FIG. 42 The electromagnetic actuator 182 is energized orde-energized under the control of an electronic control unit (ECU) 186(constituted principally by a computer) according to an output signal ofa sensor operable to detect a state of the vehicle or vehicle occupant,for example, a seat-belt sensor (SS) 185 arranged to detect that a seatbelt is worn on the vehicle operator. The seat-belt sensor 185 and theECU 186 are shown in FIG. 41. The electromagnetic actuator 182 isdisposed above the opening and closing plate 181 and supported by theholder 134, and is provided with a stopper pin 182 a. When the seat beltis worn on the vehicle operator, the electromagnetic actuator 182 isenergized to move the stopper pin 182 a downwards into the cylindricalportion 184 of the resin collar 184 fitted in the through-hole 181 a, asshown in FIG. 42. When the seat belt is not worn on the vehicleoperator, the electromagnetic actuator 182 is de-energized to retractthe stopper pin 182 a out of the cylindrical portion 184 to its upperretracted position, as shown in FIG. 43.

In the seventh embodiment arranged as described above, the forwardmovement of the opening and closing plate 181 is inhibited by thestopper pin 182 a fitted in the cylindrical portion 184 a of the resincollar 184 fitted in the through-hole 181 a, as shown in FIG. 42, byenergization of the electromagnetic actuator 182 when the seat belt isworn on the vehicle operator. In the position of the plate 181 of FIG.42, the plate 181 prevents the engagement of the engaging portion 171 bof the energy absorbing plate 171 with the recessed part 131 a 1 of theholding portion 131 a of the body-side bracket 131.

Upon collision of the vehicle while the seat belt is worn on the vehicleoperator, the break-away bracket 141 is axially moved and released fromthe body-side bracket 131 in the forward direction of the vehicle, andthe engaging portion 171 b of the energy absorbing plate 171 isaccordingly moved in the forward direction, but the engaging portion 171b is not brought into engagement with the holding portion 131 a of thebody-side bracket 131. In this event, the impact energy absorbed by theenergy absorbing plate 171 upon bending of the engaging portion 171 bdue to its abutting contact with the opening and closing plate 181 issmaller than in the sixth embodiment.

When the seat belt is not worn on the vehicle operator, on the otherhand, the electromagnetic actuator 182 is de-energized to move upwardsthe stopper pin 182 a out of the cylindrical portion 184 a of the resincollar 184 fitted in the through-hole 181 a of the opening and closingplate 181, so that the stopper pin 182 a is brought to its the upperretracted position of FIG. 43. In this case, the plate 181 receives aload larger than a force required for fracture of the cylindricalportion 184 a of the resin collar 184 (which force is smaller than aforce required for fracture of the resin capsule 42 in the sixthembodiment), so that the plate 181 is moved in the forward direction,thereby permitting the engaging portion 171 b of the energy absorbingplate 171 with the holding portion 131 a of the body-side bracket 131.

Upon collision of the vehicle while the seat belt is not worn on thevehicle operator, the break-away bracket 141 is axially moved andreleased from the body-side bracket 131 in the forward direction of thevehicle, and the engaging portion 171 b of the energy absorbing plate171 is moved in the forward direction with the bracket 141, and broughtinto abutting contact with the opening and closing plate 181, with aresult of fracturing of the cylindrical portion 184 a of the resincollar 184. Accordingly, the plate 181 is pushed in the forwarddirection by the engaging portion 171 b of the energy absorbing plate171, so that the recessed part 131 a 1 of the holding portion 131 of thebody-side bracket 131 is opened, permitting the engagement of theengaging portion 171 b of the plate 171 with the holding portion 131 aof the body-side bracket 131, as in the sixth embodiment.

The seventh embodiment employs the load changeover device 180 as meansfor selectively permitting and inhibiting absorption of the impactenergy by the energy absorbing plate 171, such that the opening andclosing plate 181 of the load changeover device 180 is permitted to bepushed forward by the engaging portion 171 b of the energy absorbingplate 171, for thereby permitting the engaging portion 171 b to bebrought into engagement with the holding portion 131 a of the body-sidebracket 131, when the seat belt is not worn on the vehicle operator.However, the load changeover device 180 may be replaced by a loadchangeover device 180 according to a first modification shown in FIG.44, or a load changeover device 200 according to a second modificationshown in FIGS. 45-47.

The load changeover device 190 of FIG. 44 is an engagement adjustingmechanism arranged to permit or inhibit the engagement of the engagingportion 171 b of the energy absorbing plate 171 with the holding portion131 a of the body-side bracket 131. The load changeover device 190includes an opening and closing plate 191 mounted on the body-sidebracket 131, and an electromagnetic actuator 192 arranged to pivot theopening and closing plate 191.

The opening and closing plate 191 is mounted on the body-side bracket131 such that the plate 191 is pivotable about a pivot pin 193 fixed tothe bracket 131, between open and closed positions in which the recessedpart 131 a 1 of the holding portion 131 a of the body-side bracket 132are respectively open and closed. The pivot pin 193 is located at asubstantially middle point in the direction of width of the slot of therecessed part 131 a 1, and in front of the holding portion 131 a. Theplate 191 has an elongate hole 191 a extending in a radial direction ofthe pivot pin 193.

The electromagnetic actuator 192 is energized or de-energized under thecontrol of the electronic control unit (ECU) 186 (constitutedprincipally by a computer) according to an output signal of a sensoroperable to detect a state of the vehicle or vehicle occupant, forexample, the seat-belt sensor (SS) 185 arranged to detect that the seatbelt is worn on the vehicle operator, as in the seventh embodiment ofFIGS. 41-43. The electromagnetic actuator 182 is disposed in front ofthe opening and closing plate 191 and supported by the body-side bracket131, and is provided with a rod 192 a having a rear end portion which isbent to have an L-shape and held in engagement with the elongate hole191 a of the plate 191.

When the seat belt is worn on the vehicle operator, the electromagneticactuator 192 is energized to move the rod 192 a in the rearwarddirection for pivoting the opening and closing plate 191 to its closedposition indicated by solid line in FIG. 44, in which the recessed part131 a 1 of the body-side bracket 131 is closed by the plate 191. Whenthe seat belt is not worn on the vehicle operator, the electromagneticactuator 192 is de-energized to move the rod 192 a in the forwarddirection for pivoting the plate 191 to the open position indicated bytwo-dot chain line in FIG. 44, in which the recessed part 131 a 1 isopen.

In the first modification shown in FIG. 44, the opening and closingplate 191 is held in its closed position indicated by solid line in FIG.44, with the rearward movement of the rod 192 a by energization of theelectromagnetic actuator 192 when the seat belt is worn on the vehicleoperator. In the closed position of the plate 191, a force of abuttingcontact of the engaging portion 171 b of the energy absorbing plate 161with the opening and closing plate 191 is simply received by the pivotpin 193, but is not transmitted to the rod 192 a, so that the plate 181is held in its closed state in which the recessed part 131 a 1 of theholding portion 131 a of the body-side bracket 131 is closed by theplate 181, so that the plate 191 prevents the engagement of the engagingportion 171 b of the energy absorbing plate 171 with the holding portion131 a of the body-side bracket 131.

Upon collision of the vehicle while the seat belt is worn on the vehicleoperator, the break-away bracket 141 is axially moved and released fromthe body-side bracket 131 in the forward direction of the vehicle, andthe engaging portion 171 b of the energy absorbing plate 171 isaccordingly moved in the forward direction, but the engaging portion 171b is not brought into engagement with the holding portion 131 a of thebody-side bracket 131. In this event, the impact energy absorbed by theenergy absorbing plate 171 upon bending of the engaging portion 171 bdue to its abutting contact with the opening and closing plate 191 issmaller than in the sixth embodiment.

When the seat belt is not worn on the vehicle operator, on the otherhand, the electromagnetic actuator 192 is de-energized to retract itsrod 192 a in the forward direction, so that the opening and closingplate 192 is pivoted to its open position in which the recessed part 131a 1 of the holding portion 131 a is held open, permitting the engagementof the engaging portion 171 b with the holding portion 131 a.

Upon collision of the vehicle while the seat belt is not worn on thevehicle operator, the break-away bracket 141 is axially moved andreleased from the body-side bracket 131 in the forward direction of thevehicle, and the engaging portion 171 b of the energy absorbing plate171 is moved in the forward direction, and brought into engagement withthe holding portion 131 a of the body-side bracket 131, as in the sixthembodiment.

In the load changeover device 190 of FIG. 44, the force of abuttingcontact of the engaging portion 171 b of the energy absorbing plate 171with the opening and closing plate 191 placed in its closed position isreceived by the pivot pin 193 and is not transmitted to the rod 192 a ofthe electromagnetic actuator 192. Further, the opening and closing plate191 is brought to its open position to permit the engagement of theengaging portion 171 b with the holding portion 131 a, so that theimpact energy absorbed by the energy absorbing plate 171 does not act onthe electromagnetic actuator 192. Accordingly, the required size andcost of manufacture of the electromagnetic actuator 192 can be reduced.

In the load changeover device 190 of FIG. 44, the opening and closingplate 191 is pivotably connected to the body-side bracket 132 throughthe pivot pin 193 and is pivoted by the rod 192 a of the electromagneticactuator 192 between its closed and open positions. However, thispivotable opening and closing plate 191 may be replaced by an openingand closing plate which is mounted on the body-side bracket 131 via asuitable holder, such that this latter plate is movable in the directionof width of the recessed part 131 a 1 of the holding portion 131 a,between its open and closed positions in which the recessed part 131 a 1is respectively open and closed.

The load changeover device 200 shown in FIGS. 45-47 is an engagementadjusting mechanism arranged to permit or inhibit the engagement of theengaging portion 171 b of the energy absorbing plate 171 with theholding portion 131 a of the body-side bracket 131. The load changeoverdevice 200 includes a support plate 135 mounted on the body-side bracket131, and an electromagnetic actuator 202 arranged to move the supportplate 135 in the longitudinal direction of the vehicle.

The support plate 135 is mounted on the body-side bracket 131 such thatthe support plate 135 is movable via a holder 136 fixed to the bracket131, in the longitudinal direction of the vehicle. The support plate 135is provided at its rear end portion with a recessed holding portion 135a, which corresponds to the holding portion 131 a provided in the sixthand seventh embodiments.

The electromagnetic actuator 202 is energized or de-energized under thecontrol of the electronic control unit (ECU) 186 (constitutedprincipally by a computer) according to an output signal of a sensoroperable to detect a state of the vehicle or vehicle occupant, forexample, the seat-belt sensor (SS) 185 arranged to detect that the seatbelt is worn on the vehicle operator, as in the seventh embodiment ofFIGS. 41-43. The electromagnetic actuator 202 is disposed in front ofthe support plate 135 and supported by the body-side bracket 131, and isprovided with a rod 202 a which is moved forward to its front positionshown in FIG. 46 by energization of the electromagnetic actuator 202when the seat belt is worn on the vehicle operator, and moved rearwardto its rear position shown in FIG. 47 by de-energization of theelectromagnetic actuator 202 when the seat belt is not worn on thevehicle operator. The rod 202 a has an externally threaded rear endportion fixed to the front end portion of the support plate 135, with apair of nuts 204.

In the second modification of FIGS. 45-47, the electromagnetic actuator202 is energized to move the rod 202 a to its front position of FIGS. 45and 46, when the seat belt is worn on the vehicle operator. In thisfront position of the rod 202 a, the engaging portion 171 b of theenergy absorbing plate 171 cannot be brought into engagement with therecessed holding portion 135 a.

Upon collision of the vehicle while the seat belt is worn on the vehicleoperator, the break-away bracket 141 is axially moved and released fromthe body-side bracket 131 in the forward direction of the vehicle, andthe engaging portion 171 b of the energy absorbing plate 171 isaccordingly moved in the forward direction, but the T-shaped engagingportion 171 b is not brought into engagement with the recessed holdingportion 135 a of the support plate 135. In this event, the impact energyabsorbed by the energy absorbing plate 171 is smaller than in the sixthembodiment.

When the seat belt is not worn on the vehicle operator, on the otherhand, the electromagnetic actuator 192 is de-energized to hold its rod202 a in the rear position of FIG. 47, so that the engaging portion 171b of the energy absorbing plate 171 can be brought into engagement withthe recessed holding portion 135 a of the support plate 135.

Upon collision of the vehicle while the seat belt is not worn on thevehicle operator, the break-away bracket 141 is axially moved andreleased from the body-side bracket 131 in the forward direction of thevehicle, and the engaging portion 171 b of the energy absorbing plate171 is moved in the forward direction, and brought into engagement withthe recessed holding portion 135 a of the support plate. 135, as in thesixth embodiment.

In the load changeover device 200 of FIG. 2. 45-47, the impact energyabsorbed by the energy absorbing plate 171 upon engagement of theengaging portion 171 b with the recessed holding portion 135 a of thesupport plate 135 is received by the body-side bracket 141 through thesupport plate 135 and the holder 136, and is not transmitted to theelectromagnetic actuator 202.

Since the impact energy absorbing load generated upon engagement of theengaging portion 171 b of the energy absorbing plate 171 with therecessed holding portion 135 a of the support plate 134 is not appliedto the electromagnetic actuator 202, the required size and cost ofmanufacture of this electromagnetic actuator 202 can be reduced.

Eighth Embodiment

A shock absorbing steering apparatus according to an eighth embodimentof this invention is illustrated in the fragmentary view of FIGS. 48-50.This eighth embodiment employs an energy absorbing plate 174 consistingof two members 174A and 174B which are movable away from each other inthe longitudinal direction of the vehicle, through an electromagneticactuator 212 disposed so as to connect and disconnect a U-shaped portion174 a and a T-shaped engaging portion 174 b of the energy absorbingplate 174 to and from each other. Namely, the present embodimentincludes a load changeover device 210 arranged to change the impactenergy absorbing load, by selectively connecting and disconnecting thetwo members 174A and 174B to and from each other. The shock absorbingsteering apparatus according to the present eighth embodiment isidentical in construction with the sixth embodiment, and has the sameadvantages as those of the seventh embodiment, in the presence of theload changeover device 210.

The load changeover device 210 includes an electromagnetic actuator 212,which is energized or de-energized under the control of the electroniccontrol unit (ECU) 186 (constituted principally by a computer) accordingto an output signal of a sensor operable to detect a state of thevehicle or vehicle occupant, for example, the seat-belt sensor (SS) 185arranged to detect that the seat belt is worn on the vehicle operator,as in the seventh embodiment of FIGS. 41-43. The electromagneticactuator 212 is fixed to the member 174A having the U-shaped portion 174a of the energy absorbing plate 174, and has a connecting pin 212 aengageable with a through-hole 174 c formed in the member 174B havingthe engaging portion 174 b of the plate 174.

The electromagnetic actuator 212 is de-energized to move the connectingpin 212 a downwards into the through-hole 174 c, as shown in FIG. 49,for thereby connecting the two members 174A, 174B of the plate 174, whenthe seat belt is not worn on the vehicle operator. When the seat belt isworn on the vehicle operator, on the other hand, the electromagneticactuator 212 is energized to move the connecting pin 212 a upwards toits upper retracted position of FIG. 50, in which the connecting pin 212a is not inserted in the through-hole 174 c. In this retracted positionof the connecting pin 212 a, the two members 174A, 174B of the energyabsorbing plate 174 are separable from each other.

In the eighth embodiment constructed as described above, the two members174A, 174B of the energy absorbing plate 174 are connected to each otherby the connecting pin 212 a inserted in the through-hole 174 c byde-energization of the electromagnetic actuator 212 when the seat beltis not worn on the vehicle operator. In this state, the energy absorbingplate 174 can effectively function to absorb the impact energy uponengagement of the engaging portion 174 b with the holding portion 131 aof the body-side bracket 131.

When the seat belt is worn on the vehicle operator, the electromagneticactuator 212 is energized to move the connecting pin 212 a to its upperretracted position in which the two members 174A, 174B of the energyabsorbing plate 174 can be disconnected from each other. In this state,the engagement of the T-shaped engaging portion 174 b of the energyabsorbing plate 174 with the holding portion 131 a of the body-sidebracket 131 does not permit the energy absorbing plate 174 toeffectively absorb the impact energy generated upon collision of thevehicle.

In the eighth embodiment described above, the energy absorbing plate 174consists of the two members 174A and 174B which are separable from eachother in the longitudinal direction of the vehicle, at the position ofthe electromagnetic actuator 212 disposed between the U-shaped portion174 a and the engaging portion 174 b of the plate 174. However, the loadchangeover device 210 provided in the eighth embodiment may be replacedby a load changeover device 220 according to a modification shown inFIGS. 51-53. In this modification, a T-shaped engaging portion 175 b ofan energy absorbing plate 175 consists of a longitudinal member 175 b 1and a transverse member 175 b 2, which are normally connected to eachother by a resin tube 223 fitted in through-holes formed in the twomembers 175 b 1, 175 b 2. The load changeover device 220 includes anelectromagnetic actuator 222 provided with a connecting pin 222 a whichis engageable with the resin tube 223.

The electromagnetic actuator 222 is energized or de-energized under thecontrol of the electronic control unit (ECU) 186 (constitutedprincipally by a computer) according to an output signal of a sensoroperable to detect a state of the vehicle or vehicle occupant, forexample, the seat-belt sensor (SS) 185 arranged to detect that the seatbelt is worn on the vehicle operator, as in the seventh embodiment ofFIGS. 41-43. The electromagnetic actuator 222 is supported by a holdermember 224 attached to the back surface of the longitudinal member 175 b1 of the engaging portion 185 b of the energy absorbing plate 175, suchthat the connecting pin 222 a can be inserted into the resin tube 223fitted in through-holes formed through the longitudinal and transversemembers 175 b 1, 175 b 2.

The electromagnetic actuator 222 is de-energized to move the connectingpin 222 a into the resin tube 223 fitted in the through-holes, as shownin FIG. 52, for thereby connecting the longitudinal and transversemembers 175 b 1, 175 b 2 of the engaging portion 175 b of the energyabsorbing plate 175 to each other, when the seat belt is not worn on thevehicle operator. When the seat belt is not worn on the vehicleoperator, the electromagnetic actuator 222 is energized to retract theconnecting pin 222 a out of the through-hole formed in the transversemember 175 b 2, as shown in FIG. 53. In this state, the longitudinal andtransverse members 175 b 1, 175 b 2 can be separated from each other byfracturing or breakage of the resin tube 223 when the engaging portion175 b is brought into engagement with the holding portion 131 a.

In the modification of FIGS. 51-53, the longitudinal and transversemembers 175 b 1, 175 b 2 of the engaging portion 175 b of the energyabsorbing plate 175 are connected to each other, with the connecting pin222 a inserted in the resin pin 223 by de-energization of theelectromagnetic actuator 222 when the seat belt is not worn on thevehicle operator. In this state, the energy absorbing plate 175effectively functions to absorb the impact energy upon engagement of theT-shaped engaging portion 175 b of the energy absorbing plate 175 withthe holding portion 131 a of the body-side bracket 131.

When the seat belt is worn on the vehicle operator, the electromagneticactuator 222 is energized to retract the connecting pin 222 a out of thethrough-hole of the transverse member 175 b 2, so that the resin tube223 is broken or fractured upon engagement of the engaging portion 175 bwith the holding portion 131 a, whereby the longitudinal and transversemembers 175 b 1, 175 b 2 of the engaging portion 175 b are separated ordisconnected from each other. In this state, the energy absorbing plate175 does not effectively function to absorb the impact energy.

Third Group of Embodiments

There will be described ninth through eleventh embodiments of thisinvention, which are similar to each other and constitute the thirdgroup of embodiments.

Ninth Embodiment

Referring to FIGS. 54-58, there is shown a shock absorbing steeringapparatus constructed according to a ninth embodiment of the presentinvention. The steering column 5 and the other elements of this steeringapparatus are similar in construction with the first embodiment. Theforegoing description of the first embodiment from the beginning up tothe portion indicated by (*1), by reference to FIGS. 1-6, applies to thesteering apparatus of this ninth embodiment. In the followingdescription of the ninth embodiment and in FIGS. 54-58, however,reference numerals 231, 241, 249 and 271 are respectively used to denotethe body-side bracket, the break-away bracket, the guide member and theenergy absorbing plate, which are denoted by respective referencenumerals 31, 41, 49 and 71 in the first embodiment. Constituent parts ofthose elements 231, 241, 249 and 271 in the ninth embodiment are denotedby combinations of those reference numerals and alphabetic letters “a”,“b”, etc.

In the ninth embodiment, the break-away bracket 241 includes a main bodyportion having an almost laterally central portion 241 cwhich consistsof two plates 241 c 1 and 241 c 2 superposed on each other, as shown inFIGS. 54-58. The upper plate 241 c 1 extends from the front end of thelower plate 241 c 2 by a suitable distance in the axial direction of thecolumn body 25. That is, the upper plate 241 c 1 includes a projectingfront end portion 241 c 3, on which a guide member 249 formed of a resinis mounted. An impact energy absorbing member in the form of an energyabsorbing plate 271 is mounted on the central portion 241 c of thebreak-away bracket 241, with the guide member 249 being interposedtherebetween. In the present embodiment, the central portion 241 c ofthe break-away bracket 241 and the guide member 249 attached to theprojecting front end portion 241 c 3 of the central portion 241 ccooperate to constitute the mounting portion 45 on which the impactenergy absorbing member in the form of the plate 271 is mounted.

The guide member 249 has a recessed portion 249 d in which theprojecting front end portion 241 c 3 of the break-away bracket 241 isfitted, and includes a semi-cylindrical portion 249 f for plasticdeformation of a lower arm section 271 a 3 of the energy absorbing plate271, which will be described. The guide member 249 further includes arear extension 249 n extending along the upper plate 241 c 1 of thebreak-away bracket 241 in the rearward direction. The guide member 49,which is thus generally J-shaped as seen in FIG. 57, is mounted on thebreak-away bracket 241 such that the rear end face of the short lowerarm is held opposed to the front end of the lower plate 241 c 2 of thebreak-away bracket 241. The rear extension 249 n has an engagingprotrusion 249 e extending downwards from its rear end. The guide member249 is mounted on the break-away bracket 241 such that the engagingprotrusion 249 e is held in engagement with the upper plate 241 c 1.

The energy absorbing plate 271 is an elongate metallic plate capable offunctioning to absorb the impact energy generated in the event of thesecondary collision of the vehicle operator with the steering wheel uponcollision of the vehicle, such that the impact energy is absorbed with aforward movement of the break-away bracket 241 relative to the vehiclebody, which takes place when the movable portion of the steering column5 is axially moved forward relative to the vehicle body by the secondarycollision. As shown in FIG. 58, the energy absorbing plate 271 includesa U-shaped portion 271 a held in engagement with the guide member 249such that the U-shaped portion 271 a is displaceable relative to thebreak-away bracket 241. The energy absorbing plate 271 further includesan engaging portion 271 b formed at its upper rear end portion. Theengaging portion 271 b is engageable with a holding portion 231 a formedon the body-side bracket 231. The energy absorbing plate 271 furtherincludes holder portions 271 c for engagement with the break-awaybracket 241.

The U-shaped portion 271 a is fitted on the two plates 241 c 1 and 241 c2 of the break-away bracket 241 and the guide member 249 of the mountingportion 45, such that opposed two straight arms of the U-shaped portion271 a sandwich the two mutually superposed plates 241 c 1, 241 c 2 ofthe break-away bracket 241 in the vertical direction, as shown in FIG.57. The U-shaped portion 271 a includes an arcuate curved section 271 a1, and the above-indicated two straight arms in the form of an upper armsection 71 a 2 and the above-indicted lower arm section 271 a 3 whichare connected together by the curved section 271 a 1. The guide member249 has a front portion held in contact with the curved section 271 a 1,and functions as a guide portion 48 operable to deform the energyabsorbing plate 271 along the curvature of the curved section 271 a 1,in pressing and sliding contact with the curved section 271 a 1. Theguide portion 48 also functions as a forcing portion operable to force adeformable member in the form of the energy absorbing plate 271, so asto cause deformation of the deformable member.

The upper straight arm section 271 a 2 extends from the upper end of thecurved section 271 a 1 rearwardly of the steering column 5, in parallelwith the upper surface of the upper plate 241 c 1 of the break-awaybracket 241. As shown in FIG. 58, the upper arm section 271 a 2 is bentat its opposite lateral ends for structural reinforcement. These bentlateral ends terminate at their rear ends in the above-indicated holderportions 271 c in the form of jaws. The above-indicated engaging portion271 b is formed by bending upwards a laterally central part of the upperarm section 271 a 2. The engaging portion 271 b has a rectangularengaging hole 271 b 1 which is engageable with the holding portion 231 ain the form of a projection formed on the body-side bracket 231. Thus,the engaging portion 271 b of the energy absorbing plate 271 isengageable with the holding portion 231 a of the body-side bracket 231.The engaging portion 271 b and the holding portion 231 a can be used toprovisionally hold the steering column 5 on the body-side bracket 231via the break-away bracket 241, when the steering column 5 is mounted onthe vehicle body through the break-away bracket 241. It is also notedthat the holder portions 271 c in the form of jaws function aspositioning and holding means for positioning and holding the upper armsection 271 a 2 with respect to the break-away bracket 241.

On the other hand, the lower straight arm section 271 a 3 extends fromthe lower end of the curved section 271 a 1 rearwardly of the steeringcolumn 5, and is held in contact with or in close proximity to the lowersurface of the lower plate 241 c 2 of the break-away bracket 241. Whenthe break-away bracket 241 is moved forward relative to the vehiclebody, the lower arm section 271 a 3 is forced by the semi-cylindricalportion 249 f of the guide member 249 (functioning as the guide portion48) in sliding contact with the semi-cylindrical portion 249 f, and isplastically deformed along the curvature of the semi-cylindrical portion249 f. This plastic deformation of the lower arm section 271 a 3 resultsin absorbing the impact energy generated upon the above-describedsecondary collision.

In the ninth embodiment constructed as described above, the U-shapedportion 271 a of the energy absorbing plate 271 is deformed by and alongthe guide member 249 mounted in the front portion of the break-awaybracket 241, in pressing and sliding contact with the semi-cylindricalportion 249 f of the guide member 249, when the break-away bracket 241is moved relative to the body-side bracket 231 in the forward directionof the vehicle in the event of the secondary collision of the vehicleoccupant upon collision of the vehicle. This deformation of the energyabsorbing plate 271 takes place while the plate 271 is displaced alongthe upper and lower surfaces of the respective upper and lower plates241 c 1 and 241 c 2, so that the impact energy generated in the event ofthe secondary collision can be absorbed, with high stability, by thedeformation of the energy absorbing plate 271.

In the event of the secondary collision, the column body 25 is axiallycontracted by more than the predetermined axial distance L1 from theinitial state shown in FIGS. 54 and 55. Described in detail, the ribs 61bof the energy absorbing member 61 undergo shearing or plasticdeformation when the upper shaft 11 and the outer tube 21 are axiallymoved relative to the lower shaft 12 and the inner tube 22,respectively, in the forward direction by more than the predeterminedaxial distance L1.

In the steering apparatus according to the present ninth embodiment, theengaging portion 271 b of the energy absorbing plate 271 is engageablewith the holding portion 231 a of the body-side bracket 231. Thisengagement can be utilized to provisionally hold the steering column 5on the vehicle body during the assembling of the steering column 5 withrespect to the vehicle body, more specifically, in the process of fixingthe steering column 5 at its break-away bracket 241 to a portion of thevehicle body (by screwing the bolts 44 into the respective nuts 32, asshown in FIG. 56). The provisional holding of the steering column 5 onthe vehicle body by engagement of the engaging portion 271 b with theholding portion 231 afacilitates the mounting of the steering column 5on the vehicle body through the break-away bracket 241. During thisprovisional holding of the steering column 5, the engaging portion 271 bis subjected to a shearing load or stress, so that the thickness of theengaging portion 271 b required to have the required strength andrigidity can be reduced, making it possible to reduce the weight of theenergy absorbing plate 271. The present steering apparatus has variousadvantages including the advantages [1]-[6] and [10]-[13] describedabove with respect to the first embodiment.

Although the ninth embodiment employing the energy absorbing plate 271shown in FIG. 58, this plate 271 may be replaced by an energy absorbingplate 272 constructed as shown in FIG. 59 according to one modificationof the ninth embodiment. This energy absorbing plate 272 includes aU-shaped portion 272 a having an upper arm section 272 a 2 and a lowerarm section 272 a 3. The upper arm section 272 a 2 is provided at itsrear end portion with an engaging portion 272 b engageable with thebody-side bracket 231, and a holder portion 272 c for engagement withthe break-away bracket 241. The engaging portion 272 b is formed bybending upwards a U-shaped section of the rear end portion of the upperarm section 272 a 2, while the holder portion 272 c is formed by bendingdownwards a rear end part of a laterally central section of the rear endportion of the upper arm section 272 a 2. The engaging portion 272 b andholder portion 272 c of the modified energy absorbing plate 272 of FIG.59 are simpler in construction than the engaging portion 271 b andholder portion 271 c of the energy absorbing plate 271 of FIG. 58.

While the holding portion 231 a of the body-side bracket 231 in theninth embodiment is arranged to cooperate with the engaging portion 271b to provisionally hold the steering column 5 on the vehicle body, theholding portion 231 a may be replaced by an engaging portion in the formof an engaging pin, for example, which is not formed integrally with thebody-side bracket 231 and which is supported by an electromagneticactuator mounted on the body-side bracket 231, as in the following tenthembodiment of the invention. In this modification, the engaging pin ismovable in opposite directions by the electromagnetic actuator, forengagement with and disengagement from the engaging portion provided forthe provisional holding of the steering column 5.

In the modification indicated above, the engaging pin retractable by theelectromagnetic actuator may function as the load changeover device andthe engagement adjusting mechanism described above. That is, where theengaging pin is held in its retracted position for disengagement fromthe engaging portion 271 b of the energy absorbing plate 271, a forwardmovement of the break-away bracket 241 relative to the vehicle body uponcollision of the vehicle does not cause plastic deformation of theU-shaped portion 271 a of the energy absorbing plate 271 in pressing andsliding contact with the guide member 249, so that the plate 271 isdisabled to absorb the impact energy.

Tenth Embodiment

The shock absorbing steering apparatus according to the tenth embodimentis shown in the fragmentary views of FIGS. 60-62. Although the energyabsorbing plate 271 used in the ninth embodiment is a single elongatemetallic plate, an energy absorbing plate 273 used in the tenthembodiment consists of two plates 273A and 273B which are superposed oneach other and each of which functions as an impact energy absorbingmember. On the other hand, the body-side bracket 231 is provided with anelectromagnetic actuator 281 fixed thereto. The electromagnetic actuator281 includes a solenoid coil, and supports an engaging pin 282functioning as a holding portion, such that the engaging pin 282 ismovable between a retracted position and an advanced position. The twoplates 273A and 273B of the energy absorbing plate 273 are engageablewith the engaging pin 282 placed in its advanced position, and notengageable with the engaging pin 282 placed in its retracted position.It is noted that the energy absorbing plate 273 may be replaced by anenergy absorbing plate consisting of three or more plates superposed oneach other.

The plate 273A includes a U-shaped portion 273Aa including an upper armsection having an engaging portion 273Ab engageable with the engagingpin 282 and a holder portion 273Ac for engagement with the break-awaybracket 241. The U-shaped portion 273Aa is fitted on the mountingportion 45 of the break-away bracket 241. The U-shaped portion 273Aafurther includes a lower arm section 273Aa3 extending below the mountingportion 45. The lower arm section 273Aa3 is plastically deformed by andalong the guide portion 48, so to absorb the impact energy generatedupon the secondary collision. The engaging portion 273Ab has arectangular engaging hole 273Ab1 which is engageable with the engagingpin 282 placed in the advanced position. The engagement of the engaginghole 273Ab1 with the engaging pin 282 can be utilized to provisionallyhold the steering column 5 on the vehicle body such that the engagingportion 273Ab is subjected to a shearing stress or load.

The other plate 273B includes a U-shaped portion 273Ba including anupper arm section having an engaging portion 273Bb engageable with theengaging pin 282 and the body-side bracket 231. The U-shaped portion273Ba is fitted at its inner surface on the outer surface of theU-shaped portion 273Aa of the plate 273A The U-shaped portion 373Bafurther includes a lower arm section 273Ba3 extending below the mountingportion 45. The lower arm section 273Ba3 is plastically deformed by andalong the guide portion 48, so to absorb the impact energy generatedupon the secondary collision. The engaging portion 273Bb has arectangular engaging hole 273Bb1 engageable with the engaging pin 282placed in the advanced position, and a pair of protruding portions273Bb2 which are spaced apart from each other in the direction of widthof the plate 273B and which are engageable with a recessed holdingportion 231 b of the body-side bracket 231. The engagement of theengaging hole 273Bb1 with the engaging pin 282 can be utilized toprovisionally hold the steering column 5 on the vehicle body such thatthe engaging portion 273Bb is subjected to a shearing stress.

The tenth embodiment of FIGS. 60-61 is substantially identical with theninth embodiment, except for the energy absorbing plate 273 and theelectromagnetic actuator 281 having the engaging pin 282. Upon collisionof the vehicle while the engaging portions 273Ab, 273Bb of the twoplates 273A, 273B with the engaging pin 282 placed in the advancedposition, the U-shaped portions 273Aa, 273Ba of the plates 273A, 273Bare deformed by and along the guide portion 48 of the break-away bracket241 while the break-away bracket 241 is moved relative to the body-sidebracket 231 in the forward direction of the vehicle. The impact energygenerated upon the vehicle collision can be absorbed with highstability, by deformation of the U-shaped portions 273Aa, 273Ba whilethese U-shaped portions are displaced relative to the break-away bracket241 along the upper and lower surfaces of the break-away bracket 241.

When the break-away bracket 241 is moved forward relative to the vehiclebody upon the vehicle collision while the engaging pin 282 is placed inthe retracted position in which the engaging portions 273Ab, 273Bb ofthe plates 273A, 273B are released from the engaging pin 282 in theretracted position, the plate 273A is not held by the body-side bracket231, and the U-shaped portion 273Aa of that plate 273A is not deformedby the forward movement of the break-away bracket 241, while the twoprotruding portions 273Bb2 of the engaging portion 273Bb of the otherplate 273B are brought into engagement with the recessed holding portion231 b of the body-side bracket 231, so that the U-shaped portion 273Baof that plate 273B is deformed by the forward movement of the break-awaybracket 241. Thus, the tenth embodiment is arranged to selectivelypermit and inhibit the deformation of the U-shaped portion 273Aa of theplate 273A, for thereby changing in two steps the amount of impactenergy that can be absorbed by the energy absorbing plate 273, dependingupon whether the seat belt is worn on the vehicle operator or not. Itwill be understood that an engagement adjusting mechanism or a loadchangeover device 285 is constituted by the engaging portions 273Ab,273Bb of the two plates 273A, 273B, the electromagnetic actuator 281 andthe engaging pin 282.

The electromagnetic actuator 281 is energized or de-energized under thecontrol of an electronic control unit (ECU) 287 (constituted principallyby a computer) according to an output signal of a sensor operable todetect a state of the vehicle or vehicle occupant, for example, aseat-belt sensor (SS) 286 arranged to detect that the seat belt is wornon the vehicle operator, as shown in FIG. 60, as in the seventhembodiment of FIGS. 41-43. The electromagnetic actuator 281 is energizedto move the engaging pin 282 to its retracted position to permit onlythe plate 273B to absorb the impact energy, when the seat belt is wornon the vehicle operator. When the seat belt is not worn on the vehicleoperator, on the other hand, the electromagnetic actuator 282 isde-energized to hold the engaging pin 282 in the advanced position forengagement with the engaging portions 273Ab, 273Bb of the two plates273A, 273B, permitting the two plates 273A, 273B to absorb the impactenergy, so that a larger amount of the impact energy can be absorbed bydeformation of the energy absorbing plate 273.

The steering apparatus according to the tenth embodiment issubstantially identical with the ninth embodiment, except for the loadchangeover device 285, and has substantially the same advantages as theninth embodiment.

In the tenth embodiment, the engaging portion 273Bb of the plate 273B isprovided with the pair of protruding portions 273Bb2, while thebody-side bracket 231 is provided with the recessed holding portion 231a, so that the protruding portions 273Bb2 of the plate 273B areengageable with the holding portion 231 a, even when the engaging pin282 is held in its retracted position by the electromagnetic actuator281. In other words, the amount of the impact energy that is absorbed bythe energy absorbing plate 273 consisting of the two plates 273A, 273Bcan be changed in two steps by the load changeover device 285. However,the load changeover device 285 of this type may be replaced by a loadchangeover device which does not include the protruding portions 273Bb2and the recessed holding portion 231 b and in which the ECU 286 isarranged to control the electromagnetic actuator 287 such that theengaging pin 282 has two retracted positions as well as the advancedposition. In one of the two retracted positions, the engaging pin 282 isreleased from the engaging portion 273Ab of the plate 273A but is heldin engagement with the engaging portion 273Bb of the other plate 273B.In the other retracted position, the engaging pin 282 is released fromthe engaging portions 273Ab, 273Bb of the two plates 273A, 273B. In thismodification, the amount of the impact energy absorbed by the energyabsorbing plate 273 can be changed in three steps corresponding to thetwo retracted positions and the advanced position of the engaging pin282.

Eleventh Embodiment

In the ninth embodiment, the steering column 5 can be provisionally heldby the vehicle body, during assembling of the steering column 5 on thevehicle body. That is, the engaging portion 271 b of the energyabsorbing plate 271 mounted on the break-away bracket 241 is broughtinto engagement with the holding portion 231 a of the body-side bracket231, to provisionally hold the steering column 5 on the vehicle body. Tothis end, the energy absorbing plate 271 is provided with the holderportions 271 c for engagement with the break-away bracket 241. In theeleventh embodiment shown in FIGS. 63 and 64, an energy absorbing plate274 different in construction from the energy absorbing plate 271 isemployed. The present eleventh embodiment is substantially identical inconstruction with the ninth embodiment, except for the energy absorbingplate 274, and has substantially the same advantages as the ninthembodiment.

The energy absorbing plate 274 employed in the eleventh embodimentincludes a U-shaped portion 274 a having a curved section 274 a 1, anupper arm section 274 a 2 and a lower arm section 274 a 3. The upper armsection 274 a 2 is provided at its rear end portion with an engagingportion 274 b which is engageable with the body-side bracket 231. Theupper arm section 274 a 2 is further provided, at its intermediateportion in front of the engaging portion 274 b, with a pair of wingportions 274 d 1, 274 d 2, which extend from the upper arm section 274 a2 in the opposite directions parallel to the direction of width of theupper arm section 274 a 2. The two wing portions 274 d 1, 274 d 2 haverespective cylindrical portions 274 e press-fitted in the resin capsules42 fitted in respective slots 241 a 1, 241 b 1 formed in the break-awaybracket 241 such that the slots 241 a 1, 241 b 1 are spaced apart fromeach other in the direction of width of the upper arm section 274 a 2(in the lateral direction of the vehicle), as shown in FIG. 63. Uponsecondary collision of the vehicle operator, the resin capsules 42 arebroken or fractured, and the cylindrical portions 274 e are releasedfrom the slots 241 a 1, 241 b 1, so that the break-away bracket 241 ispermitted to be moved relative to the body-side bracket 231. The resincapsules 42 are fitted in the respective slots 241 a 1, 241 b 1 formedin the respective arms 241 a, 241 b of the break-away bracket 241, suchthat the flanges of the resin capsules 42 are held in contact with thelower surfaces of the arms 241 a, 241 b. The two wing portions 274 d 1,274 d 2 may be considered to be a single portion formed between thecurved section 274 a 1 of the U-shaped portion 274 a and the engagingportion 274 b.

In the eleventh embodiment, the steering column 5 can be provisionallyheld by the vehicle body, by engagement of the engaging portion 274 b ofthe energy absorbing plate 274 with the holding portion 231 a, when thesteering column 5 is assembled with respect to the vehicle body. In thisprovisionally held state of the steering column 5, the weight of thesteering column 5 is received by the wing portions 274 d 1, 274 d 2 andthe engaging portion 274 b of the energy absorbing plate 274, while thecurved section 274 a 1 and the lower arm section 274 a 3 which are to bedeformed by the guide portion 48 are substantially free from a load dueto the weight of the steering column 5. Accordingly, the U-shapedportion 274 a of the energy absorbing plate 274 is not deformed duringassembling of the steering column 5 on the vehicle body, owing to theprovisional holding of the steering column 5 as described above, so thatthe energy absorbing plate 274 is capable of absorbing the impact energyin the intended manner. It will be understood that the wing portions 274d 1, 274 d 2 also function as positioning means for positioning theupper arm section 274 a 2 with respect to the break-away bracket 241.

Twelfth Embodiment

In the ninth embodiment, the curved section 271 a 1 of the U-shapedportion 271 a of the energy absorbing plate 271 is held in contact withthe semi-cylindrical portion 249 f of the guide member 249 locatedwithin the U-shaped portion 271 a. In the present twelfth embodimentemploying an energy absorbing plate 285 including a U-shaped portion 285a, there is provided a suitable amount of air gap S between the frontend of the U-shaped portion 275 a and the front end of the mountingportion 45 located within the break-away bracket 241, as shown in FIG.65. In other words, the air gap S is provided between a semi-cylindricalportion 275 a 1 of the U-shaped portion 275 a and the front end of theguide portion 48.

In the present twelfth embodiment, the air gap S permits a free forwardmovement of the break-away bracket 241 and the guide member 249, thatis, a free forward movement of the mounting portion 45, in an initialperiod of the secondary collision. Accordingly, the moment at which thedeformation of the U-shaped portion 275 a of the energy absorbing plate275 by the break-away bracket 241 is initiated is delayed with respectto the moment at which the break-away bracket 241 is released from thevehicle body (body-side bracket 231). Accordingly, the impact energyabsorbing load in the initial period of the secondary collision in thepresent twelfth embodiment is made smaller than in the apparatus whereinthe deformation of the energy absorbing plate is initiated substantiallyat the same time as the moment of releasing of the break-away bracket241 from the body-side bracket 231. The moment of generation of theimpact energy absorbing load based on the deformation of the U-shapedportion 275 a of the energy absorbing plate 275 can be adjusted asdesired, by turning the amount of the air gap S. The steering apparatusof the present twelfth embodiment is substantially identical inconstruction with the ninth embodiment, and has substantially the sameadvantages as the ninth embodiment. It will be understood that a similarair gap S may be provided in the other embodiments of this invention.

Fourth Group of Embodiments

There will be described thirteenth and fourteenth embodiments of thisinvention, which are similar to each other and constitute the fourthgroup of embodiments.

Thirteenth Embodiment

The shock absorbing steering apparatus according to the thirteenthembodiment of this invention will be described referring to a sideelevational view of FIG. 66 showing the apparatus, a plan view of FIG.67 showing a steering column 301 provided in the apparatus, a sideelevational view of FIG. 68 showing in cross section the steering column301, and perspective views of FIGS. 69A and 69B showing a rear tube 318of the steering column 301 as attached to the vehicle body and a shockabsorbing device 371 provided in the apparatus. In the steering column301 shown in FIGS. 66-68, the steering wheel is attached to the rightend of the steering column 301 as seen in these figures, while thesteering gearbox is operatively connected to the left end of thesteering column 301 as seen in the figures. The steering column 301 ismounted on the vehicle body, so as to have an inclined posture orattitude, such that the right end of the steering column 301 as seen inFIGS. 66-68 is located above and rearwardly of the left end as seen inthe figures. In the interest of simplification of description of thefollowing embodiments, the right and left ends of the steering column301 and the corresponding ends of each element thereof as seen in FIGS.66-68 will be referred to as the rear ends and the front ends,respectively, and the direction from the left end toward the rear endand the direction from the rear end toward the front end will bereferred to as the rearward and forward directions, respectively, unlessotherwise specified.

In the present steering apparatus, the steering column 301 includes acolumn body 305 as a major portion thereof, which includes a shaftportion and a tubular portion supporting the shaft portion such that theshaft portion extends through the tubular portion. The shaft portionincludes a rear shaft 310 to which a steering wheel is attached, and afront shaft 312 connected to the steering gearbox for steering frontwheels of the vehicle. The rear shaft 310 is a tubular member, while thefront shaft 312 is a rod. The front shaft 312 has a rear end portioninserted in a front end portion of the rear shaft 310. The front endportion of the rear shaft 310 has a splined inner circumferentialsurface 314, while the rear end portion of the front shaft 312 has asplined outer circumferential surface 316 held in meshing engagementwith the splined inner circumferential surface 314, such that the rearshaft 310 and the front shaft 312 are axially movable relative to eachother and are rotatable together as a unit. On the other hand, thetubular portion includes a rear tube 318 on the side of the steeringwheel, and a front tube 320 on the side of the steering gearbox. Thefront tube 320 has a rear end portion inserted in a cylindrical liner322 fitted in a front end portion of the rear tube 318, withsubstantially no clearance between the outer circumferential surface ofthe rear end portion of the front tube 320 and the inner circumferentialsurface of the cylindrical liner 322. These outer and innercircumferential surfaces of the front tube 320 and the matingcylindrical liner 322 have been subjected to a treatment for reducingtheir frictional resistance to thereby assure a smooth axial relativemovement of the rear and front tubes 318, 320. The rear tube 318 isprovided at its rear end portion with a radial bearing 324, while thefront rube 320 is provided at its front end portion with a radialbearing 326. The rear shaft 310 is rotatably supported at an axiallyintermediate portion thereof by the radial bearing 324, while the frontshaft 312 is rotatably supported at an axially intermediate portionthereof by the radial bearing 326. The column body 305 thus constructedis axially contractible and extensible. Namely, the axial length of thecolumn body 305 is variable.

The column body 305 is attached at its rear and front tubes 318 and 320to a portion of the vehicle body through respective rear and frontsupport mechanisms A and B. The front support mechanism B includes abracket 330 which is fixed to the front end portion of the front tube320 and which has a shaft hole 332 through which a support shaft (notshown) fixed to the vehicle body is inserted. Thus, the front tube 320,that is, the column body 305 is mounted to the vehicle body such thatthe column body 305 is pivotable about the support shaft of the frontsupport mechanism B. The front support mechanism A includes a columnholder structure in the form of a break-away bracket 334 fixed to aportion of the vehicle, more specifically, to a reinforcement of aninstrumental panel of the vehicle. The rear tube 318 is provided with asupported member 336 fixed thereto, while the break-away bracket 334includes a supporting member 338 of a U-shaped channel structuresupporting the supported member 336, and a supported plate 340 fixed tothe vehicle body (the reinforcement of the instrumental panel). That is,the steering column 301 includes the column body 305, the front supportmechanism B having the bracket 330, and the rear support mechanism Ahaving the break-away bracket 334.

The rear support mechanism A will be described in greater detail byreference to FIGS. 69A and 69B. The above-described reinforcement isprovided with a body-side bracket 342 fixed thereto, while the supportedplate 340 of the break-away bracket 334 has a pair of slots 344 formedthrough respective end portions that are spaced from each other in thedirection of extension of the reinforcement (in the transverse directionof the vehicle). Each of these slots 344 includes a generally circularpin hole 346 at its front end portion. The pin hole 346 has a diameterslightly larger than the width of the other portion of the slot 344.Fixing pins 348 are inserted through the respective pin holes 346 suchthat the supported plate 440 is interposed between the heads of the pins348 and the body-side bracket 342, and is thus fixed to the body-sidebracket 342. Described more specifically, an intermediate plate 350 isinterposed between the supported plate 340 and the body-side bracket342. The intermediate plate 350 has insert holes 352 in which the stemsof the fixing pins 348 are inserted, and includes annular protrusions354 extending from its lower surface. The insert holes 352 are formedthrough these annular protrusions 354, and the annular protrusions 354are fitted in the pin holes 346. Although the diameter of the fixingpins 348 is smaller than the width of the slots 344, the fixing pins 348are normally prevented from moving from the pin holes 346 through theother portion of the slots 344, in the presence of the annularprotrusions 354 fitted in the pin holes 346, so that the rear tube 318is prevented from axially moving relative to the body-side bracket 342.

The rear support mechanism A further includes a tilting mechanism 364and a telescopic mechanism 366 through which the column body 305 issupported by the break-away bracket 334. The supporting member 338 andthe supported member 336 have respective elongate holes 356 and 358,respectively. These elongate holes 356, 358 are formed such that adirection of extension of the elongate holes 356 intersects a directionof extension of the elongate holes 358. The column body 305 is pivotableabout the support shaft of the front support mechanism B, by an anglecorresponding to the length of the elongate holes 356 formed through thesupporting member 338, and is axially contractible and extensible by anaxial distance corresponding to the length of the elongate holes 358formed through the supported member 336. Referring to FIG. 66, there isshown a lock lever 362 for the tilting mechanism 364 and the telescopicmechanism 366. The lock lever 362 has a locking position indicated bysolid line and a releasing position indicated by two-dot chain line. Thesupported member 336 is firmly locked to the supporting member 338 whenthe lock lever 362 is manually operated to the locking position. In thislocking position, therefore, the tilting and axial length adjustment ofthe column body 305 by the tilting and telescopic mechanisms 364, 366are inhibited. The tilting and axial length adjustment of the columnbody 305 are permitted by operating the lock lever 362 to the releasingposition.

In the event of a secondary collision of the vehicle operator with thesteering wheel (not shown) attached to the rear shaft 310 of thesteering column 301 upon collision of the vehicle with any object, therear tube 318 is released from the vehicle body, that is, an axialmovement of the break-away bracket 334 relative to the body-side bracket342 is permitted by breakage or fracturing of the annular protrusions354 of the intermediate plate 350, which is formed of a resin or anyother material that is comparatively brittle and has a comparatively lowcoefficient of friction. Described in detail, an impact acting on thesteering wheel in the axial direction of the steering column 301 exceedsa predetermined threshold value, the annular protrusions 354 are broken,permitting a movement of the break-away bracket 334 in the forwarddirection of the vehicle while, with the supported plate 340 being movedrelative to the fixing pins 348 in the direction of extension of theslots 344, namely, relative to the vehicle body, so that the rear tube318, rear shaft 310 and break-away bracket 334 are moved togetherrelative to the vehicle body (body-side bracket 342). In the presentsteering column 301, those rear tube 318, rear shaft 310 and break-awaybracket 334 constitute a movable portion of the column body 305 which ispermitted to be axially moved relative to the vehicle body, when theimpact acting on the column body 305 exceeds the predetermined thresholdvalue. A maximum distance of axial movement of the movable portion ofthe column body 305 is defined by an abutting contact of the upper endface of the front shaft 312 with a shoulder formed on the innercircumferential surface of the rear shaft 310. However, this maximumdistance is sufficient to effectively absorb the impact energy generatedby the secondary collision, irrespective of the axial length of thecolumn body 305 as adjusted by the telescopic mechanism 366, that is,irrespective of the axial position in which the rear tube 318 and rearshaft 310 are locked with the lock lever 362 held in the lockingposition. (*3)

The present steering apparatus includes a resistance generating device370 arranged to generate a force of resistance to an axial movement ofthe steering column 301, more precisely, to an axial movement of themovable portion of the column body 305. This force of resistance may bereferred to as an impact energy absorbing load. The resistancegenerating device 370 is arranged to generate a force of resistance tothe axial movement of the movable portion of the column body 305, whichis primarily based on a force of resistance to deformation of adeformable member. The present steering apparatus includes a shockabsorbing device 371, which includes the resistance generating device370, and a mechanism which permits the axial movement of the movableportion of the column body 305. FIG. 70 shows in enlargement a portionof the resistance generating device 370 shown in FIG. 66, and FIG. 71shows in enlargement a portion of the resistance generating device 370shown in FIG. 68, while FIG. 72 is a perspective view showing a part ofthe portion of the device 370 shown in FIG. 70.

The resistance generating device 370 includes a deformable member in theform of an impact energy absorbing plate 372 (hereinafter referred to asan “EA plate 372”), and a forcing member in the form of a presser roller374 for forcing the EA plate 372 so as to cause deformation of the EAplate 372. The EA plate 372 functions as an impact energy absorbingmember arranged to generate the impact energy absorbing load, and ismounted on a mounting portion 375 of the break-away bracket 334. Themounting portion 375 is located in a substantially central portion ofthe break-away bracket 334 as seen in the transverse direction(direction of width) of the vehicle.

The presser roller 374 includes a relatively thick-walled cylindricalroller portion 376, and a shaft portion 378 inserted through a core ofthe roller portion 376 such that the roller portion 376 and the shaftportion 378 are not rotatable and axially movable relative to eachother. The shaft portion 378 is rotatably supported at its opposite endportions through respective sliding bushings by respective bearingmembers 380, 382 disposed at the front end portion of the break-awaybracket 334.

The EA plate 372 is a generally elongate strip formed of a metallicmaterial, and includes a U-shaped portion 372 a. The U-shaped portion372 a includes a curved section 372 a 1, and an upper arm section 372 a2 and a lower arm section 372 a 3 which extend in parallel with eachother from respective opposite ends of the curved section 372 a 1 in theforward direction of the vehicle. As shown in FIG. 71, the upper armsection 372 a 2 is supported on the upper surface of the supported plate340 which is a base portion of the break-away bracket 334, while thelower arm section 372 a 3 is located below and extends in parallel withan upper plate portion of the supporting member 338 which is anotherbase portion of the break-away bracket 334. The presser roller 374 isdisposed within the U-shaped portion 372 a such that the outercircumferential surface of the presser roller 374 is held in contactwith a semi-cylindrical inner surface of the curved section 372 a 1. TheEA plate 372 is mounted on a mounting portion 375 of the break-awaybracket 334, by moving the EA plate 372 in the rearward directionrelative to the mounting portion 334 such that the mounting portion 375is sandwiched by and between the upper and lower arm sections 372 a 2and 372 a 3 in a direction perpendicular to the planes of the armsections. As described below in detail, the EA plate 372 is deformed inpressing contact with the presser roller 374 when the presser roller 374is moved forward with the break-away bracket 334 as a result of aforward movement of the movable portion of the column body 25 relativeto the vehicle body in the event of a collision of the vehicle operatorwith the steering wheel upon vehicle collision. Thus, the presser roller374 held in pressing contact with the inner surface of the curvedsection 372 a 1 functions as a guide portion 385 provided in themounting portion 375, for causing deformation of the EA plate 372.

The EA plate 372 further includes an engaging portion 372 b extendingfrom the rear end of the upper arm section 372 a 2 substantiallyperpendicularly to the plane of the upper arm section, in a directionaway from the lower arm section 372 a 3. In other words, the engagingportion 372 b is formed by bending the rear end portion of the upper armsection 372 a 2 in the direction away from the lower arm section 372 a3. As shown in FIGS. 69A and 69B, the engaging portion 372 b isgenerally T-shaped, and is engageable with the body-side bracket 342when the break-away bracket 334 is moved forward relative to thebody-side bracket 342. Described in detail, the body-side bracket 342includes a holding portion 342 a having a recessed part 342 a 1. Whenthe break-away bracket 334 is moved forward relative to the body-sidebracket 342, the T-shaped engaging portion 372 b of the EA plate 372 isbrought into engagement with the holding portion 342 a of the body-sidebracket 342. When the engaging portion 372 b is brought into engagementwith the holding portion 342 a, the engaging portion 372 b receives ashearing stress or load. Before the break-away bracket 334 is movedforward relative to the body-side bracket 342, there is a free-runningdistance L2 between the engaging portion 372 b and the holding portion342 a (more precisely, the front end of a cutout formed in the recessedpart 342 a 1), as indicated in FIG. 69B, so that the engaging portion372 b (movable portion of the column body 305) is movable relative tothe holding portion 342 a by this free-running distance L2 in the eventof the secondary collision.

The EA plate 372 is positioned with respect to the mounting portion 375of the break-away bracket 334. Described in detail, the break-waybracket 334 has a rectangular hole 386, and includes a pair of U-shapedpositioning and holding pieces 388 fixed to respective opposite surfacesdefining opposite two sides of the rectangle of the rectangular hole386, as shown in FIGS. 69A and 69B. The two U-shaped positioning andholding pieces 388 are opposed to each other in the direction of widthof the EA plate 372, and are formed to position the upper and lower armsections 372 a 2, 372 a 3 of the EA plate 372. The upper arm section 372a 2 is located between the upper surface of the supported plate 340 andthe lower surfaces of the upper arms of the U-shaped positioning andholding pieces 388, so that the upper arm section 372 a 2 is positionedin the directions of width and thickness of the upper arm section 372 a2. Similarly, the lower arm section 372 a 3 is located between the lowersurface of the supported plate 340 and the upper surfaces of the lowerarms of the U-shaped positioning and holding pieces 388, so that thislower arm section 372 a 3 is also positioned in the directions of widthand thickness of the lower arm section 372 a 3. These U-shapedpositioning and holding pieces 388 function as positioning and holdingmeans for positioning and holding the upper arm section 372 a 2 withrespect to the break-away bracket 334, and positioning means forpositioning the lower arm section 372 a 3 with respect to the break-awaybracket 334. The U-shaped positioning and holding pieces 388 alsofunction as restricting members for restricting an increase in thedistance between the upper and lower arm sections 372 a 2, 372 a 3, tothereby facilitate the deformation of the deformation of the EA plate372 in pressing contact with the presser roller 374. The T-shapedengaging portion 272 b of the EA plate 272 which is engageable with theholding portion 342 a of the body-side bracket 342 has an upright partengageable with the cutout formed through the recessed part 342 a. Thisupright part has a width W1 smaller than a distance W2 between the twopositioning and holding pieces 388, as indicated in FIG. 69A, so thatthe upright part can be moved between the positioning and holding pieces388 when the EA plate 372 is mounted on the mounting portion 375 bymoving the EA plate 372 in the rearward direction relative to themounting portion 375.

The presser roller 374 carries a break-away pin 390 and a projection 392fixedly extending in opposite radial directions from one end portion ofthe shaft portion 378, as shown in FIG. 70. Where a torque applied tothe presser roller 374 is relatively small, a rotary motion of thepresser roller 374 is prevented by the break-away pin 390 in abuttingcontact with a pin-abutting member 394 fixed to the corresponding baringmember 380. Where the torque applied to the presser roller 374 is largerthan a given threshold value, the break-away pin 390 is broken or bentoff upon abutting contact of the pin 390 with the pin-abutting member394. After the break-away pin 390 is broken, a further rotary motion ofthe presser roller 374 is permitted until the projection 392 is broughtinto abutting contact with a stopper member 396 fixed to the bearingmember 380, as indicated by broken line in FIG. 70. In the presentembodiment, the presser roller 374 is permitted to be further rotated byan angle of about 45°.

When the movable portion of the column body 305 is released and axiallymoved forward from the vehicle body, as indicated by white arrow in FIG.71, that is, when the break-away bracket 334 is moved forward relativeto the body-side bracket 342, the engaging portion 372 b of the EA plate372 is brought into engagement with the holding portion 342 a of thebody-side bracket 342, and the EA plate 372 is thereafter pushed forwardby the presser roller 374 in pressing contact between. As a result, theposition of the curved section 372 a 1 in the longitudinal direction ofthe EA plate 372 is gradually changed, with deformation of the EA plate372 while the upper arm section 372 a 2 is moved rearward and the lowerarm section 372 a 3 is moved forward. Thus, the EA plate 372 is deformedas it is displaced relative to the break-away bracket 334 in pressingcontact with the presser roller 374.

Where the impact acting on the steering column 301 upon the secondarycollision is comparatively small, the movable portion of the column body305 is axially moved at a relatively low velocity. In this case, thebreak-away pin 390 is not broken upon abutting contact with thepin-abutting member 394, and a further rotary motion of the presserroller 374 is prevented, so that the EA plate 372 is deformed along thecurvature of the outer circumferential surface of the presser roller374, in pressing and sliding contact with this outer circumferentialsurface. In this respect, it is noted that the roller portion 376 of thepresser roller 374 is formed of a hard resin, so that a frictionalresistance between the roller portion 376 and the EA plate 372 iscomparatively small. Accordingly, a force required to bend the front endportion of the instantly formed lower arm section 372 a 3 along thecurvature of the presser roller 374 and straighten the front end portionof the instantly formed upper arm section 372 a 2 is considered to besubstantially equal to a force of resistance to the deformation of theEA plate 372. The resistance generating device 370 generates a resistingforce based on this force of resistance to the deformation of the EAplate 372, which is considered to be a reaction force generated by theaxial movement of the movable portion of the column body 305, whichreaction force is the impact energy absorbing load. The resisting forcebased on the force of resistance to the deformation of the EA plate 372is theoretically held constant irrespective of the velocity of the axialmovement of the movable portion of the column body 305 or the break-awaybracket 334, unless the force of resistance to the deformation of the EAplate 372 varies.

Where the impact acting on the steering column 301 is comparativelylarge, the movable portion of the column body 305 and the break-awaybracket 334 are moved at an accordingly high velocity. In this case, theEA plate 372 is forced to be deformed at a comparatively high ratewithin a relatively short time. Accordingly, the torque applied to thepresser roller 374 due to a force of friction between the roller portion376 and the EA plate 372 is increased instantaneously. As a result, thebreak-away pin 390 is broken, permitting the presser roller 374 to befurther rotated. As shown in FIG. 72, the presser roller 374 has twoshort cylindrical projections 398 formed from a metallic round rod. Thecylindrical projections 398 are partly embedded in the roller portion376, and partly project from the outer circumferential surface of theroller portion 376. The two cylindrical projections 398 are spaced fromeach other in the axial direction of the roller portion 376. On theother hand, the EA plate 372 has two parallel grooves 400 formed in oneof its opposite major surfaces such that the two grooves 400 are alignedwith the respective two grooves 400 in the axial direction of the rollerportion 376 (in the direction of width of the EA plate 372). Each of thegrooves 400 has a width slightly smaller than the diameter of thecylindrical projections 398. As the presser roller 374 is rotated, thecylindrical projections 398 come into engagement with the respectivegrooves 400, while deforming the side walls of each groove 400 so as toincrease the width of the groove 400. At this time, the force ofresistance to the deformation of the EA plate 372 is equal to a sum ofthe force required to straight and bend the upper and lower arm sections372 a 2, 372 a 3, a force required to deform above-indicated side wallsof the grooves 400, and a force of friction between the cylindricalprojections 398 and the grooves 400. This force of resistance uponengagement of the cylindrical projections 398 with the grooves 400 islarger than that before this engagement (namely, before the presserroller 374 is rotated with breakage of the break-away pin 390). Thus,the force of resistance to the deformation of the EA plate 372 isincreased with a change in the state of engagement between thedeformable member in the form of the EA plate 372 and the forcing memberin the form of the presser roller 374, so that the resisting forcegenerating by the resistance generating device 370 is accordinglyincreased. After the resisting force is increased with the engagement ofthe cylindrical projections 398 with the grooves 400, the increasedresisting force is maintained.

Referring to the graph of FIG. 73, there is schematically shown arelationship between the velocity v of movement of the movable portionof the column body 305 (more precisely, the maximum velocity v for acomparatively short time after the application of the impact to thesteering column 301) and a resisting force (impact energy absorbingload) a generated by the resistance generating device 370. It will beunderstood from this graph that a relatively large resisting force σ_(H)is generated when the velocity v is higher than a threshold value v₀above which the presser roller 374 is rotatable with the breakage of thebreak-away pin 390, and a relatively small resisting force σ_(L) isgenerated when the velocity v is lower than the threshold value v₀.Thus, the present resistance generating device 370 is considered toinclude a resistance changing mechanism operable to change the force ofresistance to the deformation of the EA plate 372, depending upon thevelocity of axial movement of the steering column 301. The amount ofimpact energy to be absorbed is a product of the distance of axialmovement of the steering column 301 and the resisting force generated bythe resistance generating device 370. In this respect, the shockabsorbing device 371 including the resistance generating device 370 isconsidered to include an impact-energy-absorption-amount changingmechanism operable to change the amount of absorption of the impactenergy depending upon the velocity of axial movement of the movableportion of the column body 305. It is also noted that the deformablemember in the form of the EA plate 372 is arranged such that theU-shaped portion 372 a is movable relative to the forcing member in theform of the presser roller 374. In other words, the presser roller 374functioning as the guide member 385 and the EA plate 372 aredisplaceable relative to each other in sliding contact with each other,at a velocity depending upon the velocity of movement of the movableportion of the column body 305. In this respect, the resistance changingmechanism of the resistance generating device 370 is considered tochange the state of engagement between the deformable member and theforcing member depending upon the velocity of the relative displacementtherebetween. The state of engagement described above is changedaccording to the torque applied to the presser roller 374, namely,according to a force which varies with the velocity of the relativedisplacement. Thus, the above-indicated impact-energy-absorption-amountchanging mechanism is arranged to change the amount of absorption of theimpact energy, depending upon the force acting thereon, without usingany electrical means.

It will also be understood from the foregoing description of thethirteen embodiment that the cylindrical projections 398 provided on thepresser roller 374 and engageable with the grooves 400 formed in the EAplate 372 function as a deformation-resistance increasing memberoperable to increase the force of resistance to the deformation of theEA plate 372, and that the mechanism for permitting the rotation of thepresser roller 374 when the velocity of movement of the break-awaybracket 334 is relatively large, that is, the mechanism including thebreak-away pin 390 and pin-abutting member 394, and the bearing members380, 382 for rotatably supporting the presser roller 374 functions as anengaging mechanism operable to bring the cylindrical projections 398into engagement with the EA plate 372 when the velocity of the relativemovement between the guide portion 385 in the form of the presser roller374 and the deformable member in the form of the EA plate 372. Thedeformation-resistance increasing member and the engaging mechanismconstitute a major portion of an energy-absorbing-load changingmechanism operable to change the impact energy absorbing load dependingupon the velocity of movement of the break-away bracket 334. Thisenergy-absorbing-load changing mechanism is arranged to increase theimpact energy absorbing load when the velocity of movement of thebreak-away bracket 334 exceeds a predetermined threshold value.

The present steering apparatus according to the thirteenth embodimenthas various advantages including the advantages [1]-[6], [8], [9], [13]and [17] described above with respect to the first embodiment, and anadditional advantage owing to the provision of the energy-absorbing-loadchanging mechanism that the amount of the impact energy that can beabsorbed is adjustable depending upon the actual impact acting on thesteering column 301 in the event of the secondary collision of thevehicle operator with the steering wheel.

Fourteenth Embodiment

The steering apparatus according to the fourteenth embodiment employs aresistance generating 410 device different from the resistancegenerating device 370 employed in the shock absorbing steering apparatusaccording to the thirteenth embodiment. The fourteenth embodiment isidentical with the thirteenth embodiment, except for the resistancegenerating device 410, which will be described referring to FIG. 74Awhich is a cross sectional view corresponding to that of FIG. 71, andFIG. 74B which is a rear elevational view of a centrifugal clutchprovided in the resistance generating device shown in FIG. 74A Theresistance generating device 410 includes a pair of bearing members (oneof which is shown in FIG. 74) 412 disposed at the front end portion of acolumn holder structure in the form of the break-away bracket 334, and apresser member in the form of a presser roller 414 rotatably supportedby the bearing members 412. The presser roller 414 is employed as aforcing member for forcing the EA plate 372 so as to cause deformationof this EA plate 372. Like the presser roller 374 employed in thethirteenth embodiment, the presser roller 414 functions as the guideportion 385 of the mounting portion 375, and includes a roller portion416 and a shaft portion 418 which are formed integrally with each other.The presser roller 414 is rotatably supported at its shaft portion 418by the pair of bearing members 412. In the present embodiment, theroller portion 416 is formed of a metallic material, having acomparatively high coefficient of friction with respect to the surfaceof the EA plate 372 (which does not have the grooves 400). The oppositeend portions of the shaft portion 418 projects from the respectivebearing members 412 in the opposite axial directions outwardly of thebearing members 412. On one of these opposite end portions, there ismounted a centrifugal clutch 420 which includes a ratchet plate 424having an outer ratchet teeth 422, and a rotary disc 426 disposedradially inwardly of the ratchet plate 424. The ratchet plate 424 has acentral hole through which the corresponding end portion of the shaftportion 418 is inserted via a sliding bushing (not shown), such that theratchet plate 424 is rotatable relative to the shaft portion 418. On theother hand, the rotary disc 426 is fixed to the shaft portion 418, at anaxial position of the shaft portion 418 outwardly of the ratchet plate424, such that the rotary disc 426 is rotated together with the presserroller 414. On the other end portion of the shaft portion 418 which isremote from the centrifugal clutch 420, there is mounted a non-toothedrotary plate (not shown) such that this rotary plate is rotatablerelative to the shaft portion 418, like the ratchet plate 424. Theratchet plate 424 and the rotary plate have the same diameter, andrespective radially protruding lugs connected to each other by aconnecting rod 428. The break-away bracket 334 has a cutout formed inits front end portion, so that the bearing members 412 are fixedlyfitted in this cutout, as shown in FIG. 74A.

A pair of pivotal levers 430 (one of which is shown in FIG. 74A) aredisposed between the two bearing members 412 such that each of thepivotal leer 430 is located adjacent to the inner surface of thecorresponding bearing member 412. The pivotal levers 430 are pivotableabout a pivot shaft 432 which is supported at its opposite ends by therespective bearing members 412. Further, the pivotal levers 430 areconnected to each other at their intermediate portions by a roller shaft434 parallel to the pivot shaft 432, so that the pivotal levers 430 arepivoted about the pivot shaft 432 as a unit, while maintaining the sameangular position. An auxiliary roller 436 having a smaller diameter thanthe presser roller 414 is rotatably mounted on the roller shaft 434. Theauxiliary roller 436 is located between the lower arm section 372 a 3 ofthe EA plate 372 and the outer circumferential surface of the rear tube318, so that pivotal motions of the pivotal levers 430 in the clockwisedirection as seen in FIG. 74A cause the auxiliary roller 436 to bebrought into pressing contact with the lower or outer surface of a frontend portion of the lower arm section 372 a 3, which is located near thecurved section 372 a 1. The free end portions of the pivotal levers 430remote from the pivot shaft 432 are arranged to be engageable with theconnecting rod 428 described above. Further, the pivotal levers 430 aresuitably curved so as to avoid an interference thereof with the EA plate372 and the presser roller 414. The two bearing members 412 areconnected to each other by a restricting rod 438, which is fixed at itsopposite ends to the respective bearing members 412. This restrictingrod 438 is located such that the restricting rod 438 is held in contactwith the upper surface of the lower arm section 372 a 3 of the EA plate372. In the present resistance generating device 410, the pivotalmotions of the pivotal levers 430 in the clockwise direction causes theauxiliary roller 436 to contact the outer surface of the lower armsection 372 a 3 of the EA plate 372, at a longitudinal position of theEA plate 372 between the presser roller 414 and the restricting rod 438which are in contact with the inner surface of the EA plate 372, so thatthe lower arm section 372 a 3 is nipped by and between the auxiliaryroller 436 and the presser roller 414 and restricting rod 438. In thisrespect, the presser roller 414 and the restricting rod 438 may beconsidered to function as a restricting member for restricting anincrease in the distance between the upper and lower arm sections 372 a2, 372 a 3 of the EA plate 372.

The centrifugal clutch 420 has an engaging jaw in the form of a pivotalpawl 440 pivotally attached to a radially outer portion of the rotarydisc 426. This engaging pawl 440 is connected at its free end to atension spring 442, so that the pivotal pawl 440 is normally releasedfrom the ratchet teeth 422. When the rotating speed of the rotary disc426, that is, the rotating speed of the presser roller 424 exceeds apredetermined threshold, a centrifugal force acting on the pivotal pawl440 becomes larger than a biasing force of the tension spring 442, sothat the pivotal pawl 440 is pivoted about its fixed end, with a resultof a movement of the free end of the pivotal pawl 440 in the radiallyoutward direction of the rotary disc 426, and engagement of the free endwith one tooth of the ratchet teeth 422. Consequently, the rotary disc426 and the ratchet plate 424 are rotated as a unit, and the pivotallevers 430 are pivoted by the connecting rod 428 in the clockwisedirection, so that the auxiliary roller 436 is brought into pressingcontact with the lower arm section 372 a 3 of the EA plate 372, wherebythe front end portion of the lower arm section 372 a 3 is curvedinwardly of the U-shaped portion 372 a, as indicated by two-dot chainline in FIG. 74A. In this state, the presser roller 414 is bound by theEA plate 372, and the rotation of the presser roller 414 is restricted,so that the EA plate 372 is deformed in frictionally sliding contactwith respect to the outer circumferential surface of the roller portion416 of the presser roller 414. Namely, when the operating state of thecentrifugal clutch 420 is changed from a released state to an engagedstate, the state of engagement between the presser roller 414 and the EAplate 372 is changed, so as to increase a force of resistance to thedeformation of the EA plate 372, so that the impact energy absorbingload is accordingly increased. Once the centrifugal clutch 420 isengaged, the centrifugal clutch 420 is locked in the engaged state, andthe rotation of the presser roller 414 is kept restricted, so that theincreased force of resistance is maintained as long as the impact energyis absorbed. In FIGS. 74A and 74B, white arrows indicate the motions ofthe various elements of the resistance generating device 410 while thecentrifugal clutch 420 is in the engaged state.

When the movable portion of the column body 305 is axially moved forwardwith a forward movement of the break-away bracket 334 relative to thebody-side bracket 342 upon the secondary collision of the vehicleoperator with the steering wheel, the EA plate 372 is deformed while aforce of resistance to the deformation of the EA plate 372 is generatedby the resistance generating device 410, as in the thirteenthembodiment. In the present fourteenth embodiment, the presser roller 414is rotated with the forward movement of the EA plate 372. When theimpact acting on the steering column 301 is comparatively small, themovable portion of the column body 305, that is, the break-away bracket334 is moved at a comparatively low velocity, and the presser roller 414is rotated at an accordingly low speed, so that the centrifugal clutch414 is not brought into its engaged state. In this state, the EA plate372 is deformed while the pressure roller 414 is rotated, so that theforce of resistance to the deformation of the EA plate 372 iscomparatively small. When the impact acting on the steering column 301is comparatively large, the movable portion of the column body 305 ismoved at a comparatively high velocity, and the presser roller 414 isrotated at an accordingly high speed, so that the centrifugal clutch 414is brought into its engaged state, with a result of an increase in theforce of resistance to the deformation of the EA plate 372, as describedabove. As in the thirteenth embodiment, the force of resistance to thedeformation is increased when the velocity v of movement of the movableportion of the column body 305 exceeds the predetermined threshold v₀,as indicated in the graph of FIG. 73. Thus, the present resistancegenerating device 410 is also considered to include a resistancechanging mechanism operable to change the force of resistance to thedeformation of the EA plate 372, depending upon the velocity of movementof the break-away bracket 334, and, a shock absorbing device 450including the resistance generating device 410 is considered to includean impact-energy-absorption-amount changing mechanism operable to changethe amount of absorption of the impact energy depending upon thevelocity of axial movement of the movable portion of the column body305.

The present fourteenth embodiment is also arranged such that theU-shaped portion 372 a of the EA plate 372 provided as a deformablemember is moved relative to the forcing member in the form of thepresser roller 414. That is, the presser roller 414 functioning as theguide portion 385 and the EA plate 372 are displaced relative to eachother at a velocity corresponding to the velocity of movement of themovable portion of the column body 305, in frictionally sliding contactwith each other. The state of engagement between the presser roller 414and the EA plate 372 is changed depending upon a centrifugal forceacting on the rotary disc 426 of the centrifugal clutch 420 which isrotated with the presser roller 414. The impact-energy-absorption-amountchanging mechanism indicted above is also arranged to change the amountof absorption of the impact energy, depending upon the force actingthereon, without using any electrical means.

In the fourteenth embodiment, the presser roller 414 functions as amovable member, more precisely, a rotatable member which is provided asthe guide portion 385 and which is rotated as the EA plate 372 isdisplaced relative to the guide portion 385. The fourteenth embodimentincludes a mechanism operable to restrict a rotary motion of the presserroller 374 when the velocity of movement of the break-away bracket 334is relatively high. That is, the centrifugal clutch 420, pivotal levers430 and auxiliary rollers 436 constitute a major portion of amovable-member-movement restricting or inhibiting mechanism operable torestrict or inhibit the rotary motion of the rotatable member in theform of the presser roller 414 when the velocity of the rotary motion isrelatively high. The movable member and the movable-member-movementrestricting or inhibiting mechanism constitute a major portion of anenergy-absorbing-load changing mechanism operable to change the impactenergy absorbing load depending upon the velocity of forward movement ofthe break-away bracket 334. This energy-absorbing-load changingmechanism is arranged to increase the impact energy absorbing load whenthe velocity of movement of forward movement of the break-away bracket334 exceeds the predetermined threshold.

The steering apparatus according to the present fourteenth embodimenthas the same advantages as the steering apparatus according to thethirteenth embodiment, including the advantage that theenergy-absorbing-load changing mechanism permits a change in the energyabsorbing load depending upon the impact actually acting on the steeringcolumn 301 upon the secondary collision of the vehicle operator with thesteering wheel.

The steering apparatus according to the fourteenth embodiment may bemodified so as to replace the resistance generating device 410 with aresistance generating device 530, which will be described by referenceto FIG. 75A which is a cross sectional view corresponding to that ofFIG. 71, and FIG. 75B which is a rear elevational view showing acentrifugal stopper 542 provided in the resistance generating device 530shown in FIG. 75A.

The present resistance generating device 530 is similar in constructionto the resistance generating device 410 provided in the fourteenembodiment of FIGS. 74A and 74B, and includes a forcing member in theform of a presser roller 532 which is rotatably supported by a firstbearing member 432 and a second bearing member (not shown) that aredisposed at the front end portion of the break-away bracket 334. Likethe presser roller 414 provided in the fourteenth embodiment, thepresser roller 534 includes a roller portion 536 and a shaft portion 538which are formed integrally with each other. The shaft portion 538 isrotatably supported at its opposite ends by the first bearing member 532and the second bearing member. The roller portion 536 is formed of ametallic material, and has a multiplicity of small projections 540formed on the outer circumferential surface such that the projections540 are evenly distributed over the entirety of the outercircumferential surface.

As is apparent from FIG. 75B, the rotary disc 426 identical with that ofthe fourteenth embodiment is fixedly mounted on the end portion of theshaft portion 538 at which the shaft portion 538 is supported by thefirst bearing member 532. The rotary plate 426 and the presser roller534 are rotated as a unit. The first bearing member 532 is formed withthe ratchet teeth 422 identical with those formed on the ratchet plate424 used in the fourteenth embodiment. That is, the first bearing member532 is equivalent to a combination of the ratchet plate 424 and thecorresponding one of the two bearing members 412 in the fourteenthembodiment. The rotary disc 426 has the pivotal pawl 440 and the tensionspring 442, as in the fourteenth embodiment. When the rotating speed ofthe presser roller 534 exceeds a predetermined threshold, a centrifugalforce acting on the pivotal pawl 440 becomes larger than the biasingforce of the tension spring 442, so that the pivotal pawl 440 is pivotedabout its fixed end, with a result of a movement of the free end of thepivotal pawl 440 in the radially outward direction of the rotary disc426, and engagement of the free end with one tooth of the ratchet teeth422, whereby a further rotary motion of the presser roller 534 isinhibited. The first bearing member 532, the rotary plate 426, thepivotal pawl 440 and the tension spring 442 constitute theabove-indicated centrifugal stopper 542, which is arranged to stop therotary motion of the presser roller 534, by utilizing the centrifugalforce. In other words, the centrifugal stopper 542 functions to lock thepresser roller 534. Like the fourteenth embodiment wherein thecentrifugal clutch 420 is not provided on the second bearing member 412,the centrifugal stopper 542 is not provided on the second bearing memberin the present modification, which is provided to merely rotatablysupport the shaft portion 538 of the presser roller 534 at thecorresponding end portion.

When the movable portion of the column body 305 is released from thevehicle body and axially moved forward relative to the vehicle body uponthe secondary collision of the vehicle operator with the steering wheel,the EA plate 372 is deformed while a force of resistance to thedeformation of the EA plate 372 is generated by the resistancegenerating device 530, as in the fourteenth embodiment. In the presentembodiment, too, the presser roller 534 is rotated with the forwardmovement of the EA plate 372. When the impact acting on the steeringcolumn 301 is comparatively small, the movable portion of the columnbody 305, that is, the break-away bracket 334 is moved at acomparatively low velocity, and the presser roller 414 is rotated at anaccordingly low speed, so that the centrifugal stopper 542 is notbrought into its operated or engaged state. In this state, the EA plate372 is deformed while the pressure roller 414 is rotated, so that theforce of resistance to the deformation of the EA plate 372 iscomparatively small. When the impact acting on the steering column 301is comparatively large, the movable portion of the column body 305 ismoved at a comparatively high velocity, and the presser roller 414 isrotated at an accordingly high speed, so that the centrifugal stopper542 is brought into its engaged state, with a result of stopping of therotary motion of the presser roller 534. In the presence of theprojections 540 held in contact with the EA plate 372, a relativelylarge force is required to move the EA plate 372 in frictionally slidingcontact with the projections 540 formed on the circumferential surfaceof the presser roller 534. Therefore, the force of resistance to thedeformation of the EA plate 372 is increased. Namely, the resistancegenerating device 530 generates an increased force of resistance to thedeformation of the EA plate 372, that is, a relatively large impactenergy absorbing load. Once the centrifugal clutch 420 is engaged, thecentrifugal clutch 420 is locked in the engaged state, and the rotationof the presser roller 414 is kept restricted, so that the increased,force of resistance is maintained as long as the impact energy isabsorbed.

In the present modification of the fourteenth embodiment, too, the stateof engagement between the deformable member in the form of the EA plate372 and the forcing member in the form of the presser roller 534 ischanged, and the generated force of resistance to the deformation of theEA plate 372 is increased, depending upon the velocity of relativemovement of the EA plate 373 and the presser roller 534. Therelationship between the velocity of movement of the movable portion ofthe column body 305 and the generated force of resistance is the same asindicated in the graph of FIG. 73. Thus, the present resistancegenerating device 530 is also considered to include a resistancechanging mechanism operable to change the force of resistance to thedeformation of the EA plate 372, depending upon the velocity of axialmovement of the steering column 301, and, a shock absorbing device 550including the resistance generating device 530 is considered to includean impact-energy-absorption-amount changing mechanism operable to changethe amount of absorption of the impact energy depending upon thevelocity of axial movement of the steering column 301. Further, thepresser roller 534 functions as a movable member, more precisely, arotatable member, and the centrifugal stopper 542 constitutes a majorportion of the movable-member movement restricting or inhibitingmechanism, which cooperates with the movable member in the form of thepresser roller 534 to constitute a major portion of theenergy-absorbing-load changing mechanism operable to change the impactenergy absorbing load depending upon the velocity of forward movement ofthe break-away bracket 334 or steering column 301. Thisenergy-absorbing-load changing mechanism is arranged to increase theimpact energy absorbing load when the velocity of movement of forwardmovement of the break-away bracket 334 exceeds the predeterminedthreshold.

Fifth Group of Embodiments

There will be described fifteenth, sixteenth and seventeenth embodimentsof this invention, which are similar to each other and constitute thefifth group of embodiments.

Fifteenth Embodiment

The fifteenth embodiment of this invention will be described referringto a side elevational view of FIG. 76 showing the apparatus, a plan viewof FIG. 77 showing the steering column 301 provided in the apparatus, aside elevational view of FIG. 78 showing in cross section the steeringcolumn 301, and perspective views of FIGS. 79A and 79B showing the reartube 318 of the steering column 301 as attached to the vehicle body anda shock absorbing device 600 provided in the apparatus. In the steeringapparatus according to the present fifteenth embodiment, theconstruction of the steering column 301, and the arrangement formounting the steering column 301 on the vehicle body, are similar tothose in the thirteenth embodiment. The foregoing description of thethirteenth embodiment from the beginning up to the portion indicated by(*3), by reference to FIGS. 66-69, applies to the steering apparatus ofthis fifteenth embodiment.

The shock absorbing device 600 is shown in the perspective views ofFIGS. 79A and 79B, a fragmentary side elevational view of FIG. 80, afragmentary side elevational view in cross section of FIG. 81, and frontelevational view of FIGS. 82A and 82B. The shock absorbing device 600 isinterposed between the rear tube 318 (movable portion of the column body305) and the vehicle body, more specifically, between the break-awaybracket 334 and the body-side bracket 342 attached to the reinforcementof the instrumental panel of the vehicle. The shock absorbing device 600includes a load generating device 604 arranged to generate an impactenergy absorbing load. The load generating device 604 includes adeformable member in the form of an impact energy absorbing plate 610(hereinafter referred to as an “EA plate 619”), and generates the impactenergy absorbing load based on a force required to cause deformation ofthe EA plate 610. The EA plate 610 is mounted on a mounting portion 611which is located in a substantially central part of the break-awaybracket 334 as seen in the transverse direction (direction of width) ofthe vehicle.

In the front end portion of the mounting portion 611 of the break-awaybracket 334, there is fixed disposed a guide member 612 formed of aresin material. The guide member 612 is a generally semi-cylindricalmember, and is mounted on the front end portions of the supported plate340 and supporting member 338 of the break-away bracket 335 which aresuperposed on each other. Described more specifically, the guide member612 has a recessed part in which the front end portions of the supportedplate 340 and supporting member 338 are fitted. The guide member 612functions as a forcing member for forcing the EA plate 372 so as tocause deformation of the EA plate 372, and constitutes a guiding portion613 of the mounting portion 611 of the break-away bracket 334. Themounting portion 611 includes a back-up plate 612 which rests on theupper surface of the supported plate 340, for backing an upper armsection 610 a 2 of the EA plate 610.

The EA plate 610 is a generally elongate strip formed of a metallicmaterial, and includes a U-shaped portion 610 a. The U-shaped portion610 a includes a curved section 610 a 1, and the above-indicated upperarm section 6102 a 2 and a lower arm section 610 a 3 which extend inparallel with each other from respective opposite ends of the curvedsection 610 a 1 in the rearward direction of the vehicle. As mostclearly shown in FIG. 81, the upper arm section 372 a 2 is supported onthe upper surface of the back-up plate 614, while the lower arm section610 a 3 is located below and extends in parallel with an upper plateportion of the supporting member 338. The curved section 610 a 1 of theEA plate 610 is held at its inner surface in contact with thesemi-cylindrical outer surface of the guide member 612. The EA plate 610is mounted on the mounting portion 611 of the break-away bracket 334, bymoving the EA plate 610 in the rearward direction relative to themounting portion 611 such that the mounting portion 611 is sandwiched byand between the upper and lower arm sections 610 a 2 and 610 a 3 in adirection perpendicular to the planes of the arm sections. The guidemember 613 is closely fitted in the U-shaped portion 610 a of the EAplate 610, so as to prevent removal of the EA plate 610. The EA plate610 further includes an engaging portion 610 b extending from the rearend of the upper arm section 610 a 2 substantially perpendicularly tothe plane of the upper arm section, in a direction away from the lowerarm section 610 a 3. In other words, the engaging portion 610 b isformed by bending the rear end portion of the upper arm section 610 a 2in the direction away from the lower arm section 610 a 3. As shown inFIGS. 79 and 82B, the engaging portion 610 b is generally T-shaped, andis engageable with the body-side bracket 342 when the break-away bracket334 is moved forward relative to the body-side bracket 342, as describedbelow in detail.

The EA plate 610 is positioned with respect to the mounting portion 611of the break-away bracket 334. Described in detail, the break-waybracket 334 has a rectangular hole 616, and includes a pair ofpositioning and holding pieces 388 fixed to respective opposite surfacesdefining opposite two sides of the rectangle of the rectangular hole616, as shown in FIGS. 79. The two positioning and holding pieces 618are provided as positioning and holding means for positioning andholding the EA plate 610 with respect to the break-away bracket 334. Thefunction of the positioning and holding pieces 618 are similar to thatof the positioning and holding pieces 388 used in the thirteenthembodiment. In the fifteenth embodiment, the upper arm section 610 a 2is supported by the underlying back-up plate 614, while the upper armsection 610 a 2 is positioned and held by the positioning and holdingpieces 618. The T-shaped engaging portion 610 b of the EA plate 610 hasan upright part engageable with a holding portion in the form of arocking body 638 (described below in detail) pivotally attached to thebody-side bracket 342. This upright part has a width WI smaller than adistance W2 between the two positioning and holding pieces 618, asindicated in FIG. 79, as in the thirteenth embodiment wherein the widthW1 is smaller than the distance W2 between the two positioning andholding pieces 388.

To the body-side bracket 342 attached to the reinforcement, there isfixed a U-shaped bracket 632 having a pair of arm portions 630, as shownin FIGS. 81, 82A and 82B. The arm portions 630 of the U-shaped bracket632 have respective shaft holes 634, and a support shaft 636 is fixed atits opposite ends in the respective shaft holes 634. The rocking body638 indicated above is pivotally supported by the support shaft 636. Therocking body 638 functions as an inertia mass, and consists of agenerally U-shaped main member 640, a weight member 642 in the form of around rod, and a cylindrical collar 644. The U-shaped main member 640includes opposite side walls 646 having respective shaft holes 648. Thesupport shaft 636 extends through the shaft holes 648 and thecylindrical collar 644, and the cylindrical collar 644 is fixed at itsopposite end faces to the opposite inner surfaces of the side walls 646.Thus, the rocking body 638 is pivotally supported by the bracket 632.The weight member 642 is fixed at its opposite end faces to the free endportions of the inner surfaces of the side walls 646. The rocking body638 has a normal or original operating position, namely, an attitude ina state of equilibrium in weight, as indicated by solid line in FIGS. 80and 81. FIG. 80 shows the steering column 301 as actually mounted on thevehicle body via the body-side bracket 342 such that the steering column301 is inclined. On the other hand, FIG. 81 shows the positionalrelationship between the shock absorbing device 600 and the rocking body638. The rocking body 638 is pivotable about an axis of the supportshaft 636, within a predetermined angular range defined by two angularpositions one of which is indicated by two-dot chain line in FIG. 81.Namely, the rocking body 638 is pivotable in the clockwise direction asseen in FIG. 81, until the weight member 642 comes into abutting contactwith a stopper 650 fixed to the U-shaped bracket 632. The angularposition of the rocking body 638 indicated by the two-dot chain line isreferred to as a “stroke end position”. FIG. 82A shows the rocking body638 placed in its normal or original position, while FIG. 82B shows therocking body 638 placed in its stroke end position.

When the impact acting on the steering column 301 exceeds apredetermined threshold in the event of a secondary collision of thevehicle operator with the steering wheel, for example, the movableportion of the column body 305 is released from the body-side bracket342 and axially moved forward, namely, the break-away bracket 334 isaxially moved forward, as in the thirteenth embodiment. In the presentembodiment, the load generating device 604 of the shock absorbing device600 generates or does not generate an impact energy absorbing load,depending upon the operating position or attitude of the rocking body638 during the forward movement of the break-away bracket 334. FIG. 83Ashows the break-away bracket 334 in the process of the forward movementwhile the rocking body 638 is placed in the original position, whileFIG. 83B shows the break-away bracket 334 when the engaging portion 610b of the EA plate 610 comes into abutting contact with a connectingportion 662 of the main member 640 of the rocking body 638 while therocking body 638 is placed in its stroke end position.

The connecting portion 662 of the main member 640 connects the two sidewalls 646, and has a recessed holding portion 664 with which theengaging portion 610 b of the EA plate 610 is engageable during theforward movement of the break-away bracket 334 while the rocking body638 is placed in the stroke end position. While the rocking body 638 isplaced in its normal or original position of FIG. 83A, the connectingportion 662 is located above the, engaging portion 610 b, the engagingportion 610 b does not come into engagement with the holding portion 664of the connecting portion 662. In this case, therefore, the EA plate 610is moved forward with the break-away bracket 334, without deformation ofthe EA plate 610. Thus, the load generating device 604 does not generatean impact energy absorbing load when the rocking body 638 is placed inthe original position. When the rocking body 638 has been pivoted fromthe original position by more than a predetermined angle toward thestroke end position, as shown in FIG. 83B, the engaging portion 610 b ofthe EA plate 610 is brought into engagement with the holding portion 664of the connecting portion 662 of the main member 640 of the rocking body638. Since this engagement of the engaging portion 610 b with theholding portion 664 prevents a further forward movement of the EA plate610 relative to the body-side bracket 342 (U-shaped bracket 632), sothat the U-shaped portion 610 a of the EA Plate 610 is deformed inpressing sliding contact with the guide member 312. Namely, the EA plate610 is deformed while it is displaced relative to the break-away bracket334, so that the load generating device 604 generates an impact energyabsorbing load based on a force required to case the deformation.

In the event of a collision of the vehicle with any object, the inertiamass in the form of the rocking body 368 is displaced, morespecifically, pivoted by an inertial force. The angle of the pivoting ofthe rocking body 368 is determined by not only the inertial force, butalso the gravity also acting on the rocking body 638 so as to preventthe pivoting. Namely, the angle of the pivoting depends on the magnitudeof the impact acting on the vehicle upon its collision. In this respect,the load generating device 604 is considered to include aninertia-mass-displacement permitting device arranged to permit adisplacement of the inertia mass depending upon the magnitude of theimpact acting on the vehicle body. The load generating device 604generates an impact energy absorbing load when the magnitude of theimpact applied to the vehicle body is larger than a threshold abovewhich the angle of the pivoting of the rocking body 638 is sufficient topermit the engagement of the engaging portion 610 b of the EA plate 610with the holding portion 664 provided on the rocking body 638.

The load generating device 604 of the shock absorbing device 600includes a first member or a forcing member in the form of the guidemember 612 which is not movable relative to the movable portion of thecolumn body 305, and a second member or a deformable member in the formof the EA plate 610 which is moved relative to and in sliding contactwith the forcing member when the movable member is moved while thedeformable member is prevented from being moved relative to the vehiclebody. The load generating device 604 generates an impact absorbing loadbased on a force required to cause deformation of the deformable memberduring its movement relative to the forcing member. The movement of thedeformable member relative to the vehicle body is permitted or inhibiteddepending upon the amount of displacement of the inertia mass in theform of the rocking body 638, so that the impact energy absorbing loadgenerated by the load generating device 604 is changed in two steps.That is, the present load generating device 604 is considered to includean energy-absorbing-load change mechanism arranged to change the impactenergy absorbing load depending upon the amount of displacement of theinertia mass 638. Further, the shock absorbing device 600 including thisload generating device 604 is considered to include animpact-energy-absorption-amount changing mechanism arranged to changethe amount of absorption of the impact energy depending upon the amountof displacement of the inertia mass.

In the present steering apparatus, the rocking body 638 which has theholding portion 664 engageable with the EA plate 610 is supported by thevehicle body such that the rocking body 638 undergoes a displacement inthe form of a pivotal motion due to an inertial force, such that theamount of the pivotal motion changes with the magnitude of the impactacting on the vehicle body in the event of a collision of the vehicle.The engaging portion 610 b of the EA plate 610 is brought intoengagement with the holding portion 664 when the amount of the pivotalmotion (displacement) of the rocking body 638 is larger than apredetermined threshold. In this respect, the present steering apparatusis considered to include an engagement adjusting mechanism arranged topermit or inhibit the engagement of the engaging portion 610 b with therocking body 638.

The steering apparatus according to the present fifteenth embodiment hasvarious advantages including the advantages [1]-[6], [13] and [17] ofthe first embodiment, and an additional advantage that theabove-described impact-energy-absorption-amount changing mechanism, orthe engagement adjusting mechanism permits the absorption of the impactenergy depending upon the magnitude of the impact generated uponcollision of the vehicle.

The rocking body 638 having the holding portion 664, which is employedin the fifteenth embodiment, may be modified as shown in FIG. 84. In asteering apparatus of FIG. 84 according to this modification of thefifteenth embodiment, one of the opposite end portions of the supportshaft 636 extends from the corresponding arm portion 630 of the U-shapedbracket 632 in the direction away from the other end portion. A spring670 is disposed on the above-indicated one end portion of the supportshaft 636, so as to bias the rocking body 638 in the counterclockwisedirection as seen in FIG. 84, as indicated by arrow-headed broken linein the figure. The above-indicated arm portion 630 is provided with astopper 672, so that the main member 640 of the rocking body 638 isnormally held in abutting contact with the stopper. 672, so as to definethe normal or original position of the rocking body 638. In thisarrangement, the clockwise pivoting of the rocking body 638 is preventedwhen the impact acting on the vehicle body upon collision of the vehicleis relatively small. The inertia-mass-displacement permitting devicedescribed above may incorporate a one-way clutch mechanism (not shown)arranged to prevent a counterclockwise pivoting motion of the rockingbody 638 back to the original position after a clockwise pivoting motionby the inertial force upon collision of the vehicle. In the fifteenthembodiment, substantially no energy absorbing load is generated by theload generating device 604 when the engaging portion 610 b of the EAplate 610 is not brought into engagement with the rocking body 638, thatis, when the impact applied to the vehicle body is smaller than thepredetermined threshold. However, a basic impact energy absorbing loadmay be generated by a device other than the load generating device 604,for example, by adjusting a coefficient of friction of the liner 322(described above with respect to the thirteenth embodiment) interposedbetween the front tube 320 and the rear tube 318, or a clearance betweenthese two tubes 320, 318.

Sixteenth Embodiment

Referring to FIGS. 85 and 86, there is shown an energy absorbing plate(EA plate) 710 mounted on the break-away bracket 334 in a steeringapparatus according to the sixteenth embodiment. A structuralarrangement for mounting the EA Plate 710 on the break-away bracket 334in this sixteenth embodiment is different from that in the fifteenthembodiment. In the other aspects, the steering apparatus of thesixteenth embodiment is identical with the fifteen embodiment, and hasvarious advantages including the advantages of the fifteenth embodiment.

In the present steering apparatus, the mounting portion 611 of thebreak-away bracket 334 does not include the guide member 612. Themounting portion 611 includes the supported plate 340 and the supportingmember 338 which are base portions of the break-away bracket 334 andwhich are superposed on each other. In this embodiment, the supportedplate 340 includes a generally U-shaped projecting portion(semi-cylindrical portion) 700 in which the front end portion of thesupporting member 338 is accommodated.

Like the EA plate 610 employed in the fifteenth embodiment, the EA plate710 includes a U-shaped portion 110 a, and an engaging portion 710 b.The U-shaped portion 710 a consists of a curved section 710 a 1, anupper arm section 710 a 2 and a lower arm section 710 a 3, and theengaging portion 710 b is formed by bending upwards the rear end portionof the upper arm section 710 a 2. The EA plate 710 is mounted on themounting portion 611 such that the curved section 710 a 1 is held at itsinner surface in close contact with the semi-cylindrical outer surfaceof the U-shaped projecting portion 700 of the supported plate 340. Whenthe break-away bracket 334 is axially moved forward relative to thevehicle body while the engaging portion 710 b of the EA plate 710 isheld in engagement with the holding portion of the body-side bracket,the EA plate 710 is deformed in pressing sliding contact with the outersurface of the U-shaped projecting portion 700. In the presentembodiment, the U-shaped projecting portion 700 functions as the guideportion 613 of the mounting portion 611. The upper arm section 710 a 2of the EA plate 710 has a pair of lugs whose front end portions areobliquely downwardly bent to form a pair of engaging jaws 710 a 4. Onthe other hand, the supported plate 340 of the break-away bracket 334has a rectangular hole 714, so that the upper arm section 710 a 2 ispositioned and held with respect to the break-away bracket 334, with theengaging jaws 710 a 4 held in engagement with the front side wall of therectangular hole 714. Thus, the pair of engaging jaws 710 a 4 functionas positioning and holding means for positioning and holding the EAplate 710 with respect to the break-away bracket 334. The EA plate 710can be easily mounted on the mounting portion 611, by moving the EAplate 710 in the rearward direction relative to the break-away bracket344, such that the mounting portion 611 is sandwiched by and between theupper and lower arm sections 710 a 2 and 710 a 3. It is noted that adimension of the rectangular hole 712 in the transverse direction of thevehicle is larger by a suitable amount than a distance between thelateral end faces of the engaging jaws 710 a 4, so that the position ofthe EA plate 710 (upper arm section 710 a 2) relative to the mountingportion 611 (supported plate 340) can be adjusted in the transversedirection of the vehicle within a distance range corresponding to theabove-indicted amount.

Referring next to FIG. 87, there is shown a modification of the mountingportion 611 employed in the sixteenth embodiment. In this modification,the supported plate 340 has a bent projecting portion 702 projectingfrom the front end of the supporting member 338. The bent projectingportion 702 has a bent end having a surface in contact with the frontend face of the supporting member 338. This bent projecting portion 702functions as the guide portion 613 of the mounting portion 611.

Seventeenth Embodiment

FIG. 88 shows an energy absorbing plate (EA plate) 740 as mounted on aportion of the vehicle body, in a shock absorbing steering apparatusconstructed according to a seventeenth embodiment of this invention.While the EA plates employed in all of the preceding embodiments aremounted on the break-away bracket attached to the steering column 301,the EA plate 740 employed in the present seventeenth embodiment ismounted on the body-side bracket 342 attached to the vehicle body. Inthe other aspects, the steering apparatus of the seventeenth embodimentis identical with that of the fifteenth embodiment.

In the present steering apparatus, the body-side bracket 342 is providedwith a channel-shaped mounting member 730 which has a mounting portion732. This mounting portion 732 is a rear end portion of an almostcentral part of the mounting member 730 as seen in the transversedirection of the vehicle. A U-shaped guide member 734 is fitted on therear end section of the mounting portion 732. Like the EA plate 610employed in the fifteenth embodiment, the EA plate 740 has a U-shapedportion 740 a including a curved section 740 a 1. The EA plate 740 ismounted on the mounting portion 732 such that the curved section 740 a 1is held at its inner surface in contact with the semi-cylindrical outersurface of the guide member 734 functioning as a guide portion 736 ofthe mounting member 732, and such that the guide member 734 issandwiched by and between upper and lower arm sections 740 a 2, 740 a 3of the EA plate 740. The EA plate 740 includes a T-shaped engagingportion 740 b formed by bending downward the front end portion of thelower arm section 740 a 3.

On a portion of the upper surface of the supported member 340 of thebreak-away bracket 334 attached to the steering body 305, which portionis located below the lower arm section 740 a 3 of the EA plate 740,there is fixedly provided a holding member 752 which has a recessedportion 750 having a recess open in the forward direction of thevehicle. This recessed portion 750 functions as a holding portion withwhich the engaging portion 740 b of the EA plate 740 is engageable whenthe movable portion of the column body 305 (break-away bracket 344) isaxially moved relative to the vehicle body (body-side bracket 342). Thecolumn body 305 is mounted on the vehicle body via the break-awaybracket 334 and the body-side bracket 342, such that there is afree-running distance L2 between the engaging portion 740 b and therecessed portion 750 (holding portion).

When the movable portion of the column body 305 is axially movedrelative to the vehicle body after the holding member 752 is broughtinto engagement with the engaging portion 740 b of the EA plate 740 inthe event of the secondary collision, the EA plate 740 is deformed inpressing sliding contact with the guide member 734 (guide portion 736),and the impact generated upon the secondary collision is absorbed by thedeformation of the EA plate 740. In the present seventeenth embodiment,an impact energy absorbing member in the form of the EA plate 740 ismounted on a portion of the vehicle body, while the holding portionengageable with the engaging portion 740 b of the impact energyabsorbing member is provided on the steering column. This embodiment isalso capable of effectively absorbing the impact energy upon thesecondary collision, and may incorporate various technical featuresprovided in the preceding embodiments and their modifications which havebeen described above.

1. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary; and an engagement adjusting mechanism operable to permit or inhibit an engagement between the engaging portion of the impact energy absorbing member and said holding portion; wherein the impact energy absorbing member is arranged to be positioned relative to the mounting portion such that the engaging portion and the holding portion are spaced from each other by a predetermined free-running distance in said forward direction before the steering column is moved in the forward direction relative to the portion of the body of the vehicle.
 2. The shock absorbing steering apparatus according to claim 1, wherein the engagement adjusting mechanism includes an actuator operable between a first position for permitting the engagement between the engaging portion and the holding portion, and a second for inhibiting said engagement.
 3. The shock absorbing steering apparatus according to claim 2, wherein the engagement adjusting mechanism is arranged such that an impact energy absorbing load to be generated by deformation of the impact energy absorbing member does not act on said actuator when the engaging portion is brought into engagement with the holding portion.
 4. The shock absorbing apparatus according to claim 1, wherein the engagement adjusting mechanism is operable to permit or inhibit the engagement between the engaging portion and the holding portion, on the basis of an output of a sensor provided to detect a state of the vehicle or an occupant of the vehicle.
 5. The shock absorbing steering apparatus according to claim 1, wherein one of the engaging portion and the holding portion includes a recessed part which has a recess engageable with the other of the engaging and holding portions and cooperates with said other to define therebetween the predetermined free-running distance.
 6. The shock absorbing steering apparatus according to claim 1, wherein the impact energy absorbing member is a plate having an end portion formed as said engaging portion.
 7. The shock absorbing steering apparatus according to claim 6, wherein the engaging portion and the holding portion are arranged such that the engaging portion receives a shearing load after the engaging portion is brought into engagement with the holding portion.
 8. The shock absorbing steering apparatus according to claim 6, wherein the impact energy absorbing member includes a plurality of plates which are superposed on each other and each of which has said engaging portion.
 9. The shock absorbing steering apparatus according to claim 6, wherein the impact energy absorbing plate includes a generally U-shaped portion consisting of a curved section and two arm sections extending from respective opposite ends of the curved section, the impact energy absorbing member being arranged to be mounted on said mounting portion such that the two arm sections extend in a direction almost parallel to a direction of movement of the steering column relative to the portion of the body of the vehicle and such that the mounting portion is sandwiched by and between the two arm sections in a direction of thickness of the plate of the impact energy absorbing member, said energy absorbing member being deformed by one end portion of the mounting portion, during the movement of the steering column relative to the portion of the body of the vehicle in the forward direction of the vehicle with the engaging portion held in engagement with the holding portion, such that a position of the curved section in the impact energy absorbing member is gradually changed, whereby the impact energy generated by the secondary collision is absorbed in the process of deformation of the impact energy absorbing member.
 10. The shock absorbing steering apparatus according to claim 9, wherein the engaging portion is formed integrally with one of the two arm sections such that the engaging portion extends, from one end of said one arm section which is remote from the curved section, in a direction away from the other of the two arm sections.
 11. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision; and an engagement adjusting mechanism operable to permit or inhibit an engagement between the engaging portion of the impact energy absorbing member and said holding portion; wherein the engagement adjusting mechanism includes a mechanism operable to cause the holding portion to be displaced by an amount corresponding to a magnitude of an impact applied to the body of the vehicle upon the collision of the vehicle, and a mechanism operable to permit the engagement between the engaging portion and the holding portion when the amount of displacement of the holding portion is larger than a predetermined threshold.
 12. The shock absorbing steering apparatus according to claim 11, wherein said mechanism operable to cause the holding portion to be displaced by the amount corresponding to the magnitude of the impact is arranged to cause a displacement of the holding portion by utilizing an inertia mass of the holding portion.
 13. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; and an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision; wherein the steering column includes a column body, and a column holder structure which holds the column body and which is fixed to said portion of the body of the vehicle such that the column holder structure is releasable and movable away from the portion of the body of the vehicle in the forward direction of the vehicle, in the event of said secondary collision, and the column holder structure includes said mounting portion while said portion of the body of the vehicle is provided with said holding portion; and the impact energy absorbing member is a plate, and includes a generally U-shaped portion consisting of a curved section and two arm sections extending from respective opposite ends of the curved section, and one of the two arm sections includes an end portion terminating in said engaging portion, the impact energy absorbing member being arranged to be mounted on said mounting portion such that the two arm sections extend in a direction almost parallel to a direction of movement of the steering column relative to the portion of the body of the vehicle and such that the mounting portion is sandwiched by and between the two arm sections in a direction of thickness of the plate of the impact energy absorbing member, the impact energy absorbing member being deformed by a front end portion of the mounting portion, during the movement of the steering column relative to the portion of the body of the vehicle in the forward direction of the vehicle with the engaging portion held in engagement with the holding portion, such that a position of the curved section in the impact energy absorbing member is gradually changed, whereby the impact energy generated by the secondary collision is absorbed in the process of deformation of the impact energy absorbing member.
 14. The shock absorbing steering apparatus according to claim 13, wherein the column holder structure includes a pair of arms which are spaced apart from each other in a lateral direction of the vehicle, and a central portion which is located almost intermediate between the pair of arms in the lateral direction, the column holder structure being fixed at the pair of arms to said portion of the body of the vehicle, and the mounting portion being located in the central portion of the column holder structure.
 15. The shock absorbing steering apparatus according to claim 13, wherein the column holder structure holds the column body through a tilting mechanism.
 16. The shock absorbing steering apparatus according to claim 13, wherein the column holder structure holds the column body through a telescopic mechanism.
 17. The shock absorbing steering apparatus according to claim 13, wherein the engaging portion is formed integrally with one of the two arms such that the engaging portion extends, from an end of said end portion of said one arm section which end is remote from the curved section, in a direction away from the other of the two arm sections.
 18. The shock absorbing steering apparatus according to claim 13, wherein the front end portion of the mounting portion is formed as a guide portion for guiding a displacement of the curved section of the impact energy absorbing member along a curvature of the front end portion while the impact energy absorbing member is deformed.
 19. The shock absorbing steering apparatus according to claim 18, wherein the mounting portion of the column holder structure consists of two plates which are superposed on each other such that one end portion of one of the two plates projects from a corresponding front end face of the other of the two plates in the forward direction of the vehicle, and the guide portion of the mounting portion is constituted by a guide member which is generally J-shaped in cross section and which has a short arm and a long arm, the guide member being fitted on said one end portion of said one plate such that a rear end face of the short arm is held opposed to the front end face of said other plate.
 20. The shock absorbing steering apparatus according to claim 18, wherein the mounting portion of the column holder structure includes a plate having a generally U-shaped projecting end portion which constitutes the guide portion.
 21. The shock absorbing steering apparatus according to claim 18, wherein the impact energy absorbing member is mounted on the mounting portion such that there is an air gap between the curved section and the guide portion.
 22. The shock absorbing steering apparatus according to claim 13, further comprising positioning and holding means for positioning and holding said one arm section of the impact energy absorbing member with respect to the column holder structure.
 23. The shock absorbing steering apparatus according to claim 22, wherein the positioning and holding means includes a pair of positioning and holding pieces disposed on opposite sides of said one arm section such that the pair of positioning and holding pieces are spaced from each other in a direction of width of said one arm section.
 24. The shock absorbing steering apparatus according to claim 23, wherein the pair of positioning and holding pieces have respective mutually opposed slant surfaces which are formed such that a distance between the opposed slant surfaces decreases in a direction from said other arm section toward said one arm section.
 25. The shock absorbing steering apparatus according to claim 24, wherein said one arm section of the generally U-shaped portion of the impact energy absorbing member is supported by a portion of the mounting portion, at an inner surface of said one arm section which faces inwardly of the generally U-shaped portion.
 26. The shock absorbing steering apparatus according to claim 23, wherein the engaging portion is formed integrally with said one arm section such that the engaging portion extends, from one end of said one arm section which is remote from the curved section, in a direction away from the other of the two arm sections and such that the engaging portion has a larger height than the pair of positioning and holding pieces, as measured from an outer surface of said one arm section that is opposite to an inner surface thereof which faces inwardly of the generally U-shaped portion, the engaging portion being engageable at a free end portion thereof with said holding portion, and having a width smaller than a distance between the pair of positioning and holding pieces, at a height position of the engaging portion which corresponds to the height of the pair of positioning and holding pieces.
 27. The shock absorbing steering apparatus according to claim 22, wherein the mounting portion includes a guide member located at a front end portion thereof and operable to guide a displacement of the curved section of the impact energy absorbing member while the impact energy absorbing member is deformed, and the guide member includes a rear extension extending in a rearward direction of the vehicle, the pair of positioning and holding means being provided on the rear extension.
 28. The shock absorbing steering apparatus according to claim 27, wherein the rear extension of the guide member includes a positioning and holding portion for positioning and holding the other of the two arm sections of the impact energy absorbing member.
 29. The shock absorbing steering apparatus according to claim 22, wherein the mounting portion includes a supporting portion, and the positioning and holding means includes a generally rectangular three-sided clip having an elastically deformable portion which cooperates with the supporting portion to elastically hold therebetween said one arm section of the generally U-shaped portion of the impact energy absorbing member in elastically pressing contact therewith in a direction of thickness of said one arm section.
 30. The shock absorbing steering apparatus according to claim 22, wherein the mounting portion includes a supporting portion, and the positioning and holding means includes a holding band which cooperates with the supporting portion to hold said one arm section of the generally U-shaped portion of the impact energy absorbing member, the holding band having a variable effective length of holding.
 31. The shock absorbing steering apparatus according to claim 13, wherein the column holder structure has a pair of slots which are spaced apart from each other in a lateral direction of the vehicle and through which the column holder structure is attached to the portion of the body of the vehicle such that the column holder structure is releasable and movable away from the portion of the body of the vehicle in the forward direction of the vehicle, the column holder structure further including a central portion which is located almost intermediate between the pair of slots in the lateral direction and which includes the mounting portion on which the impact energy absorbing member is mounted; and the impact energy absorbing member includes a pair of wing portions which extend from said one arm section in respective opposite directions parallel to the lateral direction of the vehicle and which are provided with respective cylindrical portions which are respectively press-fitted in the pair of slots of the column holder structure and which are releasable from the pair of slots when the column holder structure is moved away from the portion of the body of the vehicle in the forward direction of the vehicle.
 32. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision; and an energy-absorbing-load changing mechanism operable to change an impact energy absorbing load to be generated by deformation of the impact energy absorbing member, depending upon a velocity of the movement of the steering column in the forward direction of the vehicle relative to the portion of the body of the vehicle; wherein the energy-absorbing-load changing mechanism increases the impact energy absorbing load with an increase in the velocity of movement of the steering column.
 33. The shock absorbing steering apparatus according to claim 32, wherein the energy-absorbing-load changing mechanism changes the impact energy absorbing load by changing a force of resistance to the deformation of the impact energy absorbing member.
 34. The shock absorbing steering apparatus according to claim 33, wherein the impact energy absorbing member is a plate, and includes a generally U-shaped portion consisting of a curved section and two arm sections extending from respective opposite ends of the curved section, and one of the two arm sections includes an end portion terminating in said engaging portion, the impact energy absorbing member being arranged to be mounted on said mounting portion such that the two arm sections extend in a direction of movement of the steering column relative to the portion of the body of the vehicle and such that the mounting portion is sandwiched by and between the two arm sections in a direction almost parallel to a direction of thickness of the plate of the impact energy absorbing member, the impact energy absorbing member being deformed by an end portion of the mounting portion, during the movement of the steering column relative to the portion of the body of the vehicle in the forward direction of the vehicle with the engaging portion held in engagement with the holding portion, such that a position of the curved section in the impact energy absorbing member is gradually changed, whereby the impact energy generated by the secondary collision is absorbed in the process of deformation of the impact energy absorbing member; and said energy-absorbing-load changing mechanism includes (a) a deformation-resistance increasing member provided on said mounting portion and engageable with the impact energy absorbing member so as to increase the force of resistance to the deformation of the impact energy absorbing member, and (b) an engaging mechanism operable to cause engagement of the deformation-resistance increasing member with the impact energy absorbing member when a velocity of movement of the impact energy absorbing member relative to said front end portion of the mounting portion is higher than a predetermined threshold.
 35. The shock absorbing steering apparatus according to claim 33, The shock absorbing steering apparatus according to claim 33, wherein the impact energy absorbing member is a plate, and includes a generally U-shaped portion consisting of a curved section and two arm sections extending from respective opposite ends of the curved section, and one of the two arm sections includes an end portion terminating in said engaging portion, the impact energy absorbing member being arranged to be mounted on said mounting portion such that the two arm sections extend in a direction almost parallel to a direction of movement of the steering column relative to the portion of the body of the vehicle and such that the mounting portion is sandwiched by and between the two arm sections in a direction almost parallel to a direction of thickness of the plate of the impact energy absorbing member, the impact energy absorbing member being deformed by an end portion of the mounting portion, during the movement of the steering column relative to the portion of the body of the vehicle in the forward direction of the vehicle with the engaging portion held in engagement with the holding portion, such that a position of the curved section in the impact energy absorbing member is gradually changed, whereby the impact energy generated by the secondary collision is absorbed in the process of deformation of the impact energy absorbing member; and said energy-absorbing-load changing mechanism includes (a) a movable member provided on said mounting portion and engageable with the impact energy absorbing member such that the movable member is movable when the impact energy absorbing member is displaced relative to said front end portion of the mounting portion, and (b) a movable-member-movement restricting mechanism operable to restrict a movement of the movable member when a velocity of movement of the movable member is higher than a predetermined threshold.
 36. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision; and an initial-load adjusting mechanism operable to reduce a rate of increase of an impact energy absorbing load to be generated by the impact energy absorbing member in an initial period of the absorption of the impact energy, the initial-load adjusting mechanism being provided in at least one position selected from among: a position between the impact energy absorbing member and the portion of the body of the vehicle; a position on the impact energy absorbing member; and a position between the impact energy absorbing member and the steering column.
 37. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; and an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision; wherein the engaging portion of the impact energy absorbing member and the holding portion are engageable with each other so as to provisionally hold the steering column on the portion of the body of the vehicle through the impact energy absorbing member when the steering column is fixed to the portion of the body of the vehicle.
 38. A shock absorbing steering apparatus for use in a vehicle, comprising: a steering column to be fixed to a portion of a body of the vehicle such that the steering column is releasable from the body of the vehicle and movable in a forward direction of the vehicle in the event of a secondary collision of an occupant of the vehicle upon a collision of the vehicle, one of the steering column and said portion of the body of the vehicle including a mounting portion, and the other of the steering column and said portion of the body of the vehicle including a holding portion; an impact energy absorbing member to be mounted on the mounting portion, the impact energy absorbing member including an engaging portion which is engageable with the holding portion and being deformable as the steering column is moved in the forward direction of the vehicle while the engaging portion is held in engagement with the holding portion, whereby the impact energy absorbing member absorbs an impact energy generated by the secondary collision; and an energy-absorbing-load changing mechanism operable to change an impact energy absorbing load to be generated by deformation of the impact energy absorbing member, depending upon a velocity of the movement of the steering column in the forward direction of the vehicle relative to the portion of the body of the vehicle; wherein the energy-absorbing-load changing mechanism changes the impact energy absorbing load such that the impact energy absorbing load is larger when the velocity of movement of the steering column is higher than a predetermined threshold, than when the velocity is not higher than the predetermined threshold. 